Atmospheric Electricity and Plasma Interpretations of UFOs

Introduction

1. Définition d'un plasma
2. Occurrence des plasmas
3. Propriétés des plasmas dans la basse atmosphère
4. Le champ électrique par beau temps
5. Orages et le circuit électrique de l'atmosphère
6. Propriétés des éclairs
7. Foudre en boule
8. Coronal Effects
9. Ignis Fatuus
10. Tornado Lightning
11. Dust Devil Electricity
12. Volcano Lightning
13. Earthquake-Associated Sky Luminescence
14. Mountaintop Electricity
15. Meteor Ionization and Meteor Sounds
16. Micrométéorites d'antimatière
17. Théories des plasmas pour les ovnis
18. Plasma UFO Conference

References and Notes

Research into atmospheric electricity is important and difficult. Although many aspects are now becoming clear, much remains controversial or unknown. Even common events, such as the thunderstorm and the lightning flash, continue to provide fascinating challenges to science.

Electric fields are produced by clouds, fog, rain, sleet, snow, tornadoes, dust devils, volcanoes, earthquakes, meteors, and contaminants in air. On mountains, electrical activity often becomes intense. Experienced climbers can tell bizarre stories of mountaintop electricity. Researchers themselves have often been astonished at nature's complexity. Ball lightning, for example, although witnessed and reported many times in the past, has only with difficulty been established as a genuine scientific problem. Years of patient effort were required to distinguish ball lightning from retinal afterimages and optical illusions. In view of the numerous manifestations of atmospheric electricity, it is reasonable to try to determine whether or not some luminescent UFOs are indicative of yet another electrical phenomenon of nature.

Much research has been done theoretically, in the laboratory, and in the field that bears on the problems of atmospheric electricity and the plasma state of matter. Here we emphasize the more unusual (and often speculative) aspects of these subjects and their possible correlation with descriptions of UFO behavior. People who have witnessed unusual electrical phenomena of the types reviewed are invited to send reports to :

Dr. Bernard Vonnegut
Batiment des Sciences de la Terre, Pièce 323
Université de l'Etat de New York à Albany
1400 Washington Avenue
Albany, New York 12203

ou à leur téléphoner au to 518-457-4607 ou 518-457-3898.

L'auteur remercie les docteurs Sydney Chapman, John Firor, Sadami Matsushita, et J. Doyne Sartor du Centre National pour la Recherche Atmosphérique, et le professeur Julius London du Département d'Astrogéophysique de l'Université du Colorado, pour avoir relu des portions de ce manuscrit, pour leurs discussions instructives et agréables, et pour leurs références utiles. Il est également reconnaissant au Edmond M. Dewan des Laboratoires de Recherche de Cambridge de l'Air Force pour un dossier de réimpressions utiles.

Définition d'un plasma

Dans son état énergétique le plus faible, un atome contient un nombre égal d'électrons et de protons, et est électriquement neutre. En gagnant ou perdant des électrons, un atome ou une molécule peut acquérir une charge électrique. Une molécule ou un atome chargé est appelé un ion. Si des atomes d'un gaz deviennent des ions, le gaz est qualifié de partiellement ionisé. Lorsqu'il y a suffisamment d'ions pour affecter les propriétés physique du gaz, le gaz est appelé plasma. L'état plasmatique de la matière se réfère à un médium ionisé.

Un atome peut être ionisé en :

1. absorbant un quantum de radiation électromagnétique de haute énergie
2. entrant en collision avec un particule (atome, ion, ou électron) rapide
3. capturant un électron.

Dans les processus (1) et (2), les atomes perdent un ou plusieurs électrons et deviennent des ions positifs. Dans le processus (3), les atomes gagnent un électron et deviennent des ions négatifs. L'ionisation des couches les plus externes de l'atmosphère (au-dessus de 65 km) est causée principalement par l'absorption de rayons ultraviolets et de rayons X (processus (1)). La faible ionisation dans la basse atmosphère est pour grande partie un effet des particules des rayons cosmiques (pour la plupart des protons rapides) (processus (2)). Des électrons libres dans la base atmosphère sont rapidement capturés par les molécules d'oxygène, qui deviennent alors des ions négatifs (processus (3)).

Lorsque de grands champs électriques sont présents, les électrons et les ions sont accélerés à de grandes vitesses sur de courtes distances, et peuvent acquérir suffisamment d'énergie cinétique pour ioniser des atomes neutres lors de collisions. Les nouvelles charges sont à leur tour accélerées par le champ électrique, entrent en collision avec d'autres atomes encore neutres, et produisent plus d'électrons et d'ions. La ionisation d'un gaz neutre par accéleration de quelques électrons et ions dans un grand champ électrique est appelé processus en avalanche. Le processus en avalanche est responsable de décharges de point coronaire (feu de Saint Elme), éclairs, éclairs au néon et fluorescents, et compteurs Geiger.

Les électrons pouvant être accélerés par des champs électriques à haute fréquence, l'ionisation est parfois possible en présence de micro-ondes. Les ondes de choc à haute température entourant les météores et les véhicules spatiaux réentrants provoquent également l'ionisation dans l'atmosphère.

Lorsqu'un électron libre et ion positif entrent en collision, l'électron peut être capturé. Lorsqu'un ion négatif et un ion positif entrent en collision, un électron peut être transferé de l'ion négatif vers l'ion positif. Dans de telles collisions, appelées processus de recombinaison, les ions sont rendus neutres et deviennent des atomes ou des molécules. Dans la basse atmosphère, le plasma (tel que celui créé dans un éclair) est rapidement rendu neutre au travers de tels processus. Des radiations peuvent être émises lors de recombinaisons.

Occurrence des plasmas

Probablement 99 % de toute la matière dans l'univers est en état de plasma. Au sein des étoiles, l'hydrogène, l'helium, et les autres nombreux atomes sont complètement ionisés.

La surface visible du Soleil, appelée photosphère, est l'objet d'un phénomène curieux de plasma, le sunspot. Les forts champs magnétiques qui émanant des sunspots interagissent avec le plasma de l'atmosphère solaire externe. En conséquence, des événements violents, connus sous le nom de [flares] solaires, sont souvent générés dans les régions où le [gradient de] champ magnétique est grand. Lors des [flares] solaires, les ions et les électrons sont accélérés hors de l'atmosphère solaire dans l'espace interplanétaire. Certaines de ces particules chargées rapides interagissent avec l'environnement magnétique terrestre, et contribuent à des blackouts des ondes courtes radio, des aurores (boréales au septentrionnnales), et tempêtes géomagnetiques.

La recherche de base sur les plasmas est vitale pour de nombreux domaines technologiques. Dans le domaine de la communication, des problèmes interviennent en relation avec la transmission radio ou radar par le biais de régions de plasmas telles que la ionosphère et le [sheath] ionisé entourant un appareil spatial en rentrée atmosphérique. Des efforts en laboratoire sont en cours pour contrôler les réactions de la fusion nucléaire pour la production d'énergie. Si elles réussissent, les expériences actuelles pourraient déboucher sur des sources d'énergie efficaces qui ne nécessiteraient pas de matériaux fossiles ou fissibles. Dans le domaine de la technologie spatiale, des ingénieurs développeent des moteurs de fusée ioniques [low thrust] pour propulser la prochaine génération de vaisseaux interplanétaires.

Propriétés des plasmas dans la basse atmosphère

La basse atmosphère (en-dessous de 60 km) n'est pas un plasma sous des conditions normales. Dans chaque mètre cube d'air au niveau de la mer, l'atmosphère par beau temps contient globalement 3x10²⁵ molécules électriquement neutres et seulement 5x10⁸ ions environ. Près de 10⁷ couples d'ions sont créés apr mètre cube d'air chaque seconde par les rayons ionisants, et un nombre équivalent est rendu neutre par les processus de recombinaison. La durée de vie d'un ion de lumière est de quelques centaines de secondes. Lorsque des particules de poussière sont présentes, les ions de lumière sont rapidement absorbés, et des ions lourds de longue durée de vie sont créés. Au-dessus des terres et au niveau du sol, les rayons gamma émis par les substances radioactives naturelles sont la cause principale de l'ionization atmosphérique. Au-delà de quelques centaines de mètres au-dessus du sol, et partout ailleurs au-dessus des océans, les particules et [secondaries] des rayons cosmiques représentent la source principale d'ionisation. Dans la basse atmosphère (en-dessous de 60 km) les électrons non attachés sont immédiatement capturés par les molécules d'oxygène.

La présence de seulement quelques ions dans la base atmosphère indique que l'air n'est pas un isolant parfait. Une charge électrique placée sur une sphère de métal isolée du sol est suspendue en l'air, [will leak] dans l'atmosphère; plus l'altitude de la sphère sera élevée, plus rapide sera [the leakage] de la charge électrique.

Là où la pollution de l'air prévaut, les ions de lumière se rassemblent sur de lourdes particules de poussière, créant des ions lourds moins mobiles. La conductivité électrique de l'air pollué est souvent 10 fois moindre que celle d'un air propre.

L'atmosphère terrestre peut être présentée comme un medium diélectrique [leaky] [bounded] par des couches électriques conductrices (ou équipotentielles) au niveau de la mer et à 60 km de haut environ. Le niveau de la mer est pris comme la référence zéro ou potentiel au sol. La couche à 60 km, aujourd'hui appelée électrosphère, est le plus bas niveau dans l'atmosphère de potentiel électrique uniforme. cet article traite des effets électriques possibles dans la basse atmosphère, où les ovnis sont signalés.

Le champ électrique par beau temps

Au niveau de la mer par beau temps, il existe un champ électrique moyen d'environ 130 volt/m dirigée vers le bas. Le potentiel de l'électrosphère est d'environ 300 000 volts positif si l'on considère la surface de la Terre. La surface terrestre contient au-dessus de toute sa zone une charge négative nette de 5x10⁵ coulombs (ou 10^-9 coulomb/m²). Une charge positive égale réside dans l'atmosphère au-dessus du sol. Parce que l'air n'est pas un isolant parfait, un courant électrique de 1800 amp (ou 3,6x10^-12 amp/m²) fluctue vers le bas (i.e. les ions positifs migrent vers le bas, les ions négatifs migrent vers le haut). A de plus hautes altitudes, le courant reste constant mais le champ électrique décroît à mesure que la conductivité électrique augmente. A hauteur d'un avion de ligne (12 km), le potentiel électrique de l'air a atteint 90 % du potentiel de l'électrosphère (i.e. près de 270 000 volts).

Ceci indique que la plupart de la charge positive réside dans la troposphère sous la forme d'ions positifs.

Avec les valeurs connues pour la conductivité électrique de l'air, la charge négative à la surface de la Terre devrait [leak away] en 5 mn environ. Pour maintenir une charge négative à la surface terrestre, et par conséquent le champ électrique de la basse atmosphère, un mécanisme de chargement agissant continuement est nécessaire.

Orages et le circuit électrique de l'atmosphère

Les orages maintiennent le champ électrostatique du beau temps. Chaque heure, plusieurs centaines de milliers d'éclairs et de points de décharges coronaires transfèrent de la charge négative depuis la base des nuages orageux jusqu'au sol. La charge moyenne transmise par un éclair est estimée à 20 coulombs environ. Des ions positifs s'élèvent également du sommet des nuages orageux.

De nombreuses théories ont été proposées pour expliquer comment les charges négatives et positives sont séparées dans un nuage orageux. Le mécanisme doit :

1. donne une charge positive à la part supérieure du nuage et une charge négative à la partie inférieure du nuage
2. fournir un rythme de séparation de charge de quelques ampères.

Il est généralement admis que lorsque les particules de précipitations tombent elles acquièrent une charge négative. De la sorte, une charge négative est transportée jusqu'en bas du nuage. Une compréhension détaillée des mécanismes impliqués dans le transfert de charge entre les particules de précipitations (et les polluants de l'air) est d'une importance scientifique majeure.

Une preuve solide que les nuages orageux agissent comme des batteries pour l'atmosphère est fournie au travers des fluctuations journalières du champ électrique du beau temps. Au-dessus des océans le champ électrique du beau temps fluctue de 15 à 20 % de sa valeur [mean], et atteint un maximum à 19 h 00 Greenwich Mean Time partout au-dessus de la terre indépendamment du temps local. Des maximas secondaires plus petits interviennet à 15 h 00 GMT et à 07h 00 GMT. La plupart de l'activité orageuse de la Terre intervient dans les régions tropicales au milieu de l'après-midi lorsque la chaleur de surface est la plus apte à produire une forte convection. A 19 h 00 GMT, c'est le milieu de l'après-midi dans la bassin de Amazone ; à 15 h 00 GMT, c'est le milieu de l'après-midi en Afrique ; à 07 h 00 GMT, c'est le milieu de l'après-midi en Indonesie. Le champ magnétique de beau temps minimum existe à 03 h 00 GMT, au milieu de l'après-midi au milieu de l'Océan Pacifique.

Si chaque orage fournit un courant chargeant de 1 amp, il doit y avoir au moins 1800 orages tonnant en même temps au-dessus de la terre à tout moment pour maintenir le champ électrique du beau temps. Ce n'est pas un estimations déraisonnable. Il semble probable, par conséquent, que les orages soient la cause première de l'activité électrique de la Terre.

Propriétés des éclairs

Des élévations subites dans l'atmosphère sont connues sous le terme de foudre. L'éclair limite la magnitude du dipôle électrique d'un nuage orageux. Seulement 20 % environ de l'ensemble des éclairs de foudre sont entre le nuage et le sol. La majorité des éclairs a lieu au sein des nuages. Ici nous décrivons brièvement uniquement l'événement de nuage-à-sol, pour lequel de meilleures informations sont disponibles.

Ce qui apparaît pour l'œil comme un seul éclair de foudre correspond en fait à un certain nombre d'élévations indiviuelles de charge électrique, appelées courses, se répétant en successions rapides. Un éclair consiste en entre 1 et 40 courses principales, chacune d'entre elles étant précédée d'une course directrice. Le nombre médian de courses dans un éclair de foudre est d'environ 3.

Lorsque les forces d'un champ électrique s'accumulent jusqu'à des valeurs d'environ 3 x 10⁶ volt/m près du bord du nuage, les processus d'avalanche deviennent importants. L'événement de foudre visible commence avec l'initiation d'un stepped leader depuis la région du nuage où le champ électrique est le plus intense. Ce stepped leader est un canal conducteur, peut-être de quelques cm de diamètre, qui essentiellement au même potentiel que la base du nuage. En conséquence, à mesure que le leader progresse vers le bas en s'éloignant du nuage, le champ électrique (i.e. le gradient potentiel) entre le bout du leader et l'air environnant s'accroît continuellement, de sorte qu'une ionisation ultérieure devienne plus aisée.

Après être avancée de 20 m environ (la distance exacte dépend de la force du champ), le leader fait une pause pendant environ 50 microsecondes, va de l'avant sur encore 20 m, s'arrête à nouveau, et ainsi de suite (on pense que l'ionisation de l'air immédiatement au-dessus du stepped leader est initiée par une région d'avalanche region nommée pilot streamer). Le stepped leader avance vers le bas en direction du sol selon une trajectoire de zigzag globablement parallèle au champ électrique. Après 100 étapes environ et 50 millisecondes, le stepped leader a presque traversé les 2 km ou à peu près entre le base du nuage et le sol. Losque le stepped leader descend à environ 20 m d'altitude, il rencontre un streamer positif venant de la terre (la différence de potentiel entre le nuage et le sol pourrait atteindre 10⁸ ou 10⁹ volts avant un éclair de foudre).

Dès que le canal conducteur entre le nuage et le sol et établi, la course (ou retour) principal commence. En moins de 10 microsecondes, un courrant d'environ 20 000 amp force son passage à travers un canal conducteur de seulement quelques millimètres de diamètre (le courrant maximum jamais enregistré est un éclair de foudre qui faisait 345 000 amp). En moyenne, environ 10⁹ joules (une énergie équivalente à 1/4 de t de TNT) sont dégagées lors de l'événement de l'éclair.

La température dans le canal de foudre, mesurée spectroscopiquement, atteint 30 000 °K seulement 12 microsecondes après le passage de l'extrêmité de la course de retour, mais se dissipe si rapidement qu'elle tombe à 5 000 °K en quelques 50 microsecondes. Si la thermalisation est achevée, ces températures ne sont pas suffisamment chaudes pour provoquer une dissociation et ionisation considerable des molécules d'air. Certains scientifiques disent, cependant, que les températures thermales ne dépassent jamais quelques milliers de degrés Kelvin. La variation temporelle précise de la température thermale est importante pour estimer les dégats de la foudre par chocs acoustiques.

Les forces de champ magnétique associées à la foudre sont autour de 1 tesla (=10⁴ gauss), de sorte que l'effet de plasma pinch est probablement important. Les possibles effets magnétiques d'une course de foudre ont été considérés en relation avec la foudre en boule et en perle.

Après la 1ʳᵉ course leader et de retour, l'éclair de foudre pourrait se poursuivre avec une autre élévation de courant le long du même canal conducteur. Cette 2nde course est initiée par un dart leader, qui advance de manière continue (par par étapes) et plus rapidement que le stepped leader. Le dart leader suit le canal principal vers le sol et ignore les canaux de branches sous terre de la 1ʳᵉ course. Lorsque le dart leader atteint le sol, une course de retour suit.

Les processus de recombinaison travaillent rapidement dans l'atmosphere. Seulement 100 millisecondes après la cessation d'une course de retour, le canal de foudre n'est plus suffisamment conducteur pour guider un dart leader. L'éclair de foudre est alors terminé. Une autre course depuis la même partie d'un nuage doit suivre une trajectoire complètement nouvelle, une créée par un nouveau stepped leader. Pour cette raison, les signalements de foudre en boule durant aussi longtemps que quelques secondes ont été écartés ou considérés comme étant des images rémanentes de l'œil. Il n'existe pas d'explication satisfaisante pour une luminescence isolée de longue durée dans l'atmosphère.

Foudre en boule

Parmi les manifestations les plus mystérieuses de l'électricité atmosphérique est le phénomène de foudre en boule, ou Kugelblitz. Un boule lumineuse soit :

1. apparaissant après un éclair d'un nuage vers le sol et restant près du sol, soit
2. d'abord vue en l'air, descendant d'un nuage ou arising from no obvious cause, thereafter remaining aloft until it vanishes.

Les collisions avec un appareil ont provoqué des dommages vérifiés, indiquant que la foudre en boule n'est pas restreinte au niveau du sol.

La plupart des témoins indiquent que la foudre en boule est clairement visible le jour bien que non aussi brillante qu'un éclair ordinaire. Quelques 85 % des observateurs s'accordent sur le fait que la taille et la brillance de la boule restent globalement constantes tout au long de la période d'observation et qu'aucun changement n'intervient même jusqu'à sa disparition. Une minorité signale des changements de brillance et de couleur juste avant que la boule disparaissent. Les couleurs rouge, orange et jaune sont les plus courantes, mais la plupart des autres couleurs sont vues occasionnellement. Certains chercheurs pensent que les Kugelblitz bleu ou bleu-blanc sont associés à une plus grande énergie, bien qu'il n'y ait aucune base statistique pour une telle assertion. Les diamètres de Kugelblitz rapportés varient de 5 à 80 cm avec une moyenne d'environ 30 cm. Une étude répertorie 3 [complexions] de foudre en boule :

1. une apparence solide avec une surface mâte ou réfléchissante, ou un cœur solide avec une enveloppe translucide
2. une structure rotative, suggérant des mouvements internes
3. une structure avec une apparence de feu.

Le dernier type semble plus commun. Près de 1/3 des témoins détectent des mouvemenst internes ou une rotation de la boule elle-même, bien que cela puisse dépendre de la distance de l'observateur.

Une majorité de témoins rapportent le mouvement de la boule comme étant lent (environ 2 m/s) et horizontal, sans guidage apparente par le vent ou par le sol. 1 observateur sur 6 signale des vitesses dépassant 25 m/s. Plusieurs signalements indiquent bien un guidage par les lignes téléphoniques ou électriques et par des objets au sol. Une odeur de brimstone (soufre brûlant) est souvent rapportée par les observateurs proches, en particulier au moment de l'affaiblissement.

La durée moyenne de la foudre en boule en grossièrement de 4 s, avec 10 % signalant plus de 30 s. La détermination de la durée de vie est difficile car :

1. le temps subjectif durant un événement excitant est souvent erroné, et
2. peu d'observateurs voient une boule du moment où elle est créée jusqu'au moment où elle disparaît.

Dans tous les cas, un canal d'éclair ordinaire pouvant rester électriquement conducteur pendant seulement 0,1 s, une durée de 10 s est de 2 ordres de magnitude au-delà de ce qui est attendu.

Il n'y a pas longtemps, une discussion scientifique considérable s'ensuivi sur la question de savoir si la foudre en boule était un phénomène réel. Les scientifiques pensaient que la foudre en boule pouvait être :

1. l'image rétinienne persistante d'un éclair,
2. une décharge intense de point coronaire près de la cible d'un éclair sous un nuage orageux,
3. un matériau brûlant ou incandescent projeté depuis le point d'impact d'un [bolt] d'éclair.

Today most researchers believe that Kugelblitz is a genuine electrical effect. A recent survey indicates that ball lightning may be extremely commonplace, but that the observer must be relatively close to the ball to be able to see it. Kugelblitz is probably invisible or indistinguishable in daylight at distances greater than 40 meters, which would explain why it is incorrectly believed to be a rare phenomenon.

The median distance between an observer outdoors and ball lightning is 30 meters. Sometimes ball lightning floats through buildings. The median distance between indoor observers and ball lightning is only 3 meters. The reported distance of the observer seems to be closely correlated with the reported size of the ball. A more distant observer is

1. less likely to notice luminous balls of small diameter, and
2. more likely to misjudge the diameter.

The second difficulty is somewhat mitigated since in most cases of ball lightning terrestrial landmarks can be used for reference in estimating distances and sizes. On the other hand, estimates of the distance and size of a luminous sphere seen against the sky can be quite inaccurate.

In one report, a red lightning ball the size of a large orange fell into a rain barrel which contained about 18 liters of water. The water boiled for a few minutes and was too hot to touch even after 20 minutes. Assuming

1. that the water temperature was initially 20°C,
2. that 1 liter of water evaporated, and
3. that 17 liters were raised to 90°C,

one needs roughly 8x10⁶ joules of energy (equivalent to 2 kg of TNT). For a ball 10 cm in diameter (the size of a large orange), the energy density is then 5x10⁹ joule/m³. But if all the air in a volume were singly-ionized, the energy density would be only 1.6x10⁸ joule/m³. Both the energy content and the energy density of ball lightning as derived from the singular rain barrel observation seem incompatible with the non-explosive character of most Kugelblitz. Although many lightning balls emit a loud explosive (or implosive) noise upon decay, effects characteristic of the release of energies of the order of 2 kg of TNT have rarely been reported (understandably if the observer was within 3 meters) . Moreover, explosive or implosive decays have been noted indoors with no apparent heat or damage to nearby ceramic objects. Nevertheless, there are enough well-documented cases of extremely high energy Kugelblitz to make the water barrel report very believable. Probably there is a wide range of possible energies for a lightning ball, with the vast majority of Kugelblitz possessing energy densities less than that of singly-ionized air. The minimum possible energy of a lightning ball is that required to illumine a sphere about 25 cm in diameter with the brightness of a fluorescent lamp. With 10% efficiency, this means a source of 250 watts for 4 sec., or about 1000 joules of energy. We can only conclude with certainty that the energy of a lightning ball lies somewhere between 10³ and 10⁷ joules.

Theoretical efforts have focused on the energy estimate of the rain barrel observation. To maintain a fully-ionized, perhaps doubly-ionized mass of air requires either

1. a large amount of energy concentrated in a small volume and shielded from the surrounding air by a remarkably stable envelope, or
2. a continuous energy flow into a small volume, presumably by focusing power from the environment.

Theories which attempt to bottle fully-ionized plasma by magnetic fields or magnetovortex rings are faced with severe stability problems. There is no known way to contain plasma in the atmosphere for as long as a few seconds. Moreover, a fully-ionized plasma ball would be hotter and probably less dense than the surrounding air, so that it would tend to rise rather than descend or move horizontally. Chemical combustion theories cannot explain the high energy content or the remarkable antics of the ball. Nuclear reactions would require an electric potential of at least 10⁶ volts between the center and surface of the ball, and a mean free path for the ions as long as the potential gap. This situation seems unlikely, and faces similar problems of stability.

Theories which depend on an outside source of energy such as microwaves or concentrated d-c fields cannot explain how ball lightning can survive indoors.

If energies as high as several megajoules are not required, we can try other hypotheses. One suggestion is that the lightning ball is a miniature thundercloud of dust particles, with a very efficient charge separation process. Continuous low energy lightning flashes are illuminating the cloud. Another idea is that a small amount of hydrocarbon, less than that required for combustion, is suddenly subjected to strong electric fields. The hydrocarbons become ionized and form more complex hydrocarbon molecules which clump together. Eventually there is enough combustible material in the center to allow a burning core. If the concentration of hydrocarbon decreases, the ball disappears if the concentration increases, the ball ignites explosively. (This represents the swamp gas theory for ball lightning).

Much depends on a reliable energy estimate for the Kugelblitz. If the energy is as high as indicated by the water barrel report, we have a real dilemma. At present no mechanism has been proposed for Kugelblitz which can successfully explain all the different types of reports. Probably several completely different processes can produce luminescent spheres in the atmosphere.

We conclude this section with summaries of several eyewitness reports of Kugelblitz.

The first few cases concern aircraft.

1. A commercial airliner (LI-2) was struck by ball lightning on 12 August 1956 while flying in the lower Tambosk region of the USSR. Before being struck, the aircraft had been flying at 3.3 km altitude through a slowly moving cold front which contained dense thunderclouds. During a penetration of one thundercloud, where the air temperature was about -3°C, the crew saw a rapidly approaching dark red almost orange fireball 25 to 30 cm in diameter to the front and left of the aircraft. At a distance of not more than 30 to 40 cm in front of the nose, the ball swerved and collided with a blade of the left propeller, exploded in a blinding white flash, and left a flaming tail along the left side of the fuselage. The sound of the explosion was loud enough to be heard over the noise of the engine. No substantial damage could be found. One of the left propeller blades had a small fused area 4 cm along the blade and less than 1 cm in depth. Around the damaged region was a small area of soot, which was easily wiped off.
2. In 1952, a T-33 jet trainer was flying near Moody AFB in Georgia. Because of a thunderstorm, the pilot was told to proceed to Mobile, Ala. As the T-33 rolled out onto a westerly heading at 4 km altitude, it collided with a "big orange ball of fire" that hit the nose head-on. The jolt was such that the student pilot believed there had been a midair collision with another aircraft. The low frequency radio compass no longer functioned, and they had to receive radio guidance to another base. On examination of the aircraft, they did not find a single mark or hole. The only damage was to the radio compass unit in the nose of the T-33 which was practically melted inside and was rendered useless. After the radio compass was replaced, everything functioned normally.

1. Another pilot distinguishes ball lightning from balls of St. Elmo's fire, and states that he has only seen "true" ball lightning near severe thunderstorms associated with squall lines, mountainous terrain, and significant cloud-to-cloud lightning. He defines "true" ball lightning as having the following characteristics:
   1. diameters between 15 and 30 meters,
   2. never originates outside the main thunderstorm cloud,
   3. generates from a single point and expands in exactly the same manner as the fireball of an atomic explosion, but with a longer lifetime,
   4. earphones detect soft sibilant hiss, easily distinguishable from crash static, which gradually increases in loudness concurrent with the growth of the ball, then rapidly decreases in loudness after peak brightness,
   5. no apparent thunder.

   He considers smaller luminous balls seen near his aircraft to be St. Elmo's fire. If Kugelblitz within clouds can be as large as is estimated by this pilot, then ground-based observations reflect only weak manifestations of the phenomenon.

2. In Klass's book there is a remarkable photograph taken by an RCAF pilot in 1956, which seems to confirm the above observations. The pilot was flying westward at 11 km altitude over the foothills of the Canadian Rockies near Macleod, Alberta, through what he describes as the most intense thunderstorm he ever saw in North America. Cloud pillars extended above 12 km. The sun was setting behind the mountains and was obscured from view. The ground was dark. Through a break in the clouds he observed a bright stationary light with sharply defined edges "like a shiny silver dollar." The light was nestled deep within the thunderstorm, suspended above some cumulus reported at 4 km altitude. The object remained in view for 45 seconds as he flew across the cloud break. The diameter of the light is estimated to be at least 15 to 30 meters.

The following case is indicative of high-energy ball lightning.

1. At 3:30 p.m. on 26 April 1939, following a moderate rainstorm at Roche-fort-sur-Nier (France), an extremely brilliant flash of lightning branched into three directions. At the first impact point, a witness described a ball 15 to 20 cm in diameter and 2.5 meters above the ground which passed only 4 meters in front of him. He felt a breeze of air at the same time. The globe climbed an iron cable which it melted and pulverized, producing smoke in the process. The electrical conduits of an adjoining house were burned and the meter was damaged. The observer, who was installing a gas pipe, received a shock. At the second impact point several workers saw a globe also 15 to 20 cm in diameter touch the top of a crane. There ensued a great explosive noise accompanied by a blue spark as large as an arm which flew 40 meters and struck the forehead of a dock worker, knocking him to the ground. A dozen shovelers working 10 to 50 meters from the crane received shocks and were knocked over, one being thrown 60 cm into the air. The shovels were torn from their hands and thrown 3 or 4 meters away. No smoke or odor was perceived. At the crane, current flowed along the electric cable, boiled the circuit breaker board and the windings of the crane's electric motor. The chief electrician received a violent shock and was unable to free his hands from the controls. At the third impact point, a ball of fire as large as two fists hit a lightning rod and descended along the conductor to the ground, disappearing behind a building. Two workers saw a ball of fire roll very rapidly along the ground.
2. In Hanover, Germany during a July thunderstorm in 1914, a fireball the size of an egg came through the window, left a burnt spot near the ceiling, traveled down the curtain, and disappeared in the floor. No burnt marks were found in the floor or curtains, but the ceiling had a slightly charred mark the size of a penny.

Cases like these are not unusual. Ball lightning has been known to cut wires and cables, to kill or burn animals and people, to set fire to beds and barns, to chase people, to explode in chimneys, and to ooze through keyholes and cracks in the floor. It has even been reported in the passenger compartment of a DC-3 aircraft. Moreover, lightning conductors are not always able to dissipate the energy of Kugelblitz. In St. Petersburg, Fla., during the summer of 1951 an elderly woman was found burned to death in an armchair near an open window. Above one meter, there were indications of intense heat - melted candles, cracked mirror, etc. A temperature of 1400°C would have been needed to produce such effects. But below one meter there was only one small burned spot on the rug and the melted plastic cover of an electric outlet. A fuse had blown, stopping a clock in the early morning hours. Since lightning is common near St. Petersburg, this case has all the marks of Kugelblitz.

1. Le le 3 Sunday, Diane de France, fille illégimite de Henri II, alors le Dauphin, épouse Francois de Montmorency. La nuit de leur mariage, une flamme oscillante entre dans leur chambre par la fenêtre, se déplace de coin en coin, puis finalement sur le lit nuptial, où il brûle les cheveux de Diane et and night attire. Elle ne leur fit aucun autre mal, mais on peut imaginer leur frayeur.

Effets coronaires

A sharp point which extends from a charged conducting surface is a region of maximum electric field. During a thunderstorm, therefore, we can expect large electric fields near trees, towers, tall buildings, the masts of sailing ships, and all other points rising from the earth's conducting surface.

If the electric field becomes large enough, avalanche processes can cause electrical breakdown of the surrounding air and a sustained coronal discharge. Coronal effects may transfer more charge between cloud and ground than does lightning.

St. Elmo's fire appears as a glowing luminescence hovering above a pointed object or near a wire conductor. It is usually oval or ball-shaped, between 10 and 40 cm in diameter, and has a glowing blue-white appearance. Its lifetime exceeds that of ball lightning, sometimes lasting several minutes. The decay is silent but may be sudden or slow. Sometimes hissing or buzzing noises can be detected.

The primary difference between ball lightning and St. Elmo's fire is that St. Elmo's fire remains near a conductor. It has been observed to move along wires and aircraft surfaces, sometimes pulsating. Foo-fighters are probably a manifestation of St. Elmo's fire. Eyewitness reports of coronal discharge are presented in Section 14. Here is an account of St. Elmo's fire from the same pilot who gave observation 3 of the previous section.

The smaller 'ball lightning' I have always associated as being the phenomenon known as St. Elmo's fire; however, St. Elmo's fire generally consists of an infrequent blanket covering the leading edges and trailing edges of an aircraft. It does not blind or brighten but is merely irritating as it prevents clear radio reception. The 'small ball' formation varies in size from two inches (5 cm) to a foot and a half (46 cm) in diameter and generally 'rolls around' the aircraft apparently unaffected by the movement of the aircraft. On one occasion a small ball (about six inches (15 cm) in diameter) of yellowish-white lightning formed on my left tiptank in an F-94B then rolled casually across the wing, up over the canopy, across the right wing to the tiptank and thence commenced a return, which I didn't note, but I was advised by my observer that it disappeared as spontaneously as it had arisen. I have seen this form several times but rarely for as long as a period which I would estimate to be about two minutes in duration. Sometimes the balls are blue, blue-green, or white though it appears to favor the blue-green and yellow-white. It might be of interest to you to know that subsequent to the 'small ball' rolling over my aircraft, the aircraft was struck three times by conventional lightning bolts which melted four inches (10 cm) off the trailing edge of each tiptank and fused about a four inch section covering my tail lights.

Ignis fatuus

In swamps and marshes, methane, CH₄ (and also phosphine PH₃), is released by decaying organic matter. When the methane ignites, either by spontaneous combustion or by electrical discharges produced during times of thunderstorm activity, luminous globes which float above the swamp can be seen. These are not plasma effects, but resemble them in appearance. They are called Ignis Fatuus (foolish fire), jack-o-lanterns,will-o-the~wisp, or simply swamp (or marsh) gas. The colors are reported to be yellow, sometimes red or blue. Thunderstorms and other electrical activity around swamps seem to stimulate this effect.

Occasionally observers have placed their hands into these luminescent gases without feeling any heat. Dry reeds did not catch fire. Copper rods did not heat up. Occasionally however paper was ignited.

There is little doubt that Ignis Fatuus is the source of some ghost stories and UFO reports.

Tornado Lightning

In certain situations, cold dry air (from the Rocky Mountains) flows over warm moist air (from the Gulf of Mexico) which is moving in a different horizontal direction. As a result, wind shear and strong convection produce active thunderstorm cells along a line of instability some tens of kilometers ahead of the cold front. These thunderstorm cells and the opaque clouds connecting them are known as a squall line. Squall lines are the source of most tornadoes.

The characteristic feature of the tornado is the funnel-shaped cloud that hangs from the sky and moves around like the trunk of an elephant. The destructive capability of the tornado is the result of an extremely sudden pressure drop of roughly 0.1 atmosphere between the inside and outside of the funnel. Winds can range in speed from 100 to 330 m/sec.

Without question, the most concentrated and powerful manifestations of atmospheric electricity occur in conjunction with tornadoes. Tornadoes are associated with continuous lightning, point discharges, and ball lightning. Early theories of the 19^th century maintained that the tornado is a conducting channel for lightning between cloud and ground. Present thought attributes the origin of tornadoes to violent convective air motions near squall lines.

Although many convective events, such as isolated thunderstorms, dust devils, hurricanes, etc., occur in the atmosphere, these have energy concentrations much smaller than that of a tornado. Consequently, several researchers believe that a tornado can be maintained only by an intense and continuous lightning discharge along its axis. Such a discharge heats the air within the funnel, thereby causing violent updrafts and vortex motions. Whether or not this theory is correct, there is little doubt that the electrical power generated during a single tornado event is at least 2 x 10¹⁰ watts, or about 1/10 of the combined power output of all the electrical generators in the United States.

From radio emissions (spherics), it is estimated that about 20 lightning flashes occur each second in a tornado cloud. Assuming 20 coulombs per lightning discharge, the average current flowing through a tornado is about 400 amperes. Magnetic field measurements near a tornado indicate that such a current is not unreasonable. Using 10⁹ joules per lightning flash, we find 2x10¹⁰ watts for the electrical power generated by a tornado.

Such estimates may be too conservative. Tornado lightning is reported to be brighter, bluer, and more intense than its thunderstorm counterpart. Long before a tornado is observed, lightning interlaces the clouds. About 15 minutes prior to the appearance of the funnel, the lightning becomes intense and continuous. After the funnel descends, the sky is reported to be in a blaze of light with never ceasing sheet lightning.

Large hailstones are commonly produced both by tornadoes and by severe isolated thunderstorms. Hail is closely correlated with intense electrical activity. Observations of burned, wilted, and dehydrated vegetation, and odors of brimstone (burning sulfur) provide further evidence of electrical action. The tornado funnel is usually preceded by a peculiar whining sound, a noise indicative of coronal discharge.

Eyewitness accounts are interesting in the present context because it has been suggested that many UFOs are luminous tornado clouds whose funnels have not reached the ground:

1. Après qu'une tornade soit passée au-dessus de Norman, Oklahoma et se soit dirigée vers le Nord, le personnel de Tinker Field entendit a sharp hissing sound overhead combined with a low-pitched continuous roar. We were conscious of an unusual and oppressive sensation. The noise source was definitely above us. When it was nearest us, I saw the sky above gradually grow lighter, then fade to black. The light was greenish in color. Associated with the light was a strong sensation of heat radiating downward. The noise increased in volume and then faded out as though it came from the south and passed us going north. The rain had stopped while this phenomenon was overhead."
2. "As the storm was directly east of me, I could see fire up near the top of the funnel that looked like a child's Fourth of July pinwheel. There were rapidly rotating clouds passing in front of the top of the funnel. These clouds were illuminated only by the luminous band of light. The light would grow dim when these clouds were in front, and then it would grow bright again as I could see between the clouds. As near as I can explain, I would say that the light was the same color as an electric arc-welder but very much brighter. The light was so intense that I had to look away when there were no clouds in front of it."
3. The funnel from the cloud to the ground was lit up. It was a steady deep blue light -- very bright. It had an orange-color fire in the center from the cloud to the ground. As it came along my field, it took a swath about 100 yards wide. As it swung from left to right, it looked like a giant neon tube in the air, or a flagman at a railroad crossing. As it swung along the ground level, the orange fire or electricity would gush out from the bottom of the funnel and the updraft would take it up in the air causing a terrific light -- and it was gone! As it swung to the other side, the orange fire would flare up and do the same."
4. There was a screaming, hissing sound coming directly from the end of the funnel. I looked up, and to my astonishment I saw right into the heart of the tornado. There was a circular opening in the center of the funnel, about fifty to one hundred ft. (15 to 30 m) in diameter and extending straight upward for a distance of at least half a mile (800 m), as best I could judge under the circumstances. The walls of this opening were rotating clouds and the whole was brilliantly lighted with constant flashes of lightning, which zigzagged from side to side."
5. We looked up into what appeared to be an enormous hollow cylinder bright inside with lightning flashes, but black as blackest night all round. The noise was like ten million bees plus a roar that beggars all descriptions."
6. A few minutes after the storm passed, there was a taste and smell in the air like that of burnt sulfur. The air was clammy, and it was hard for me to breathe. The sensation was like being smothered."
7. ... burned up the trees that lay within its circumference, and uprooted those which were upon its line of passage. The former, in fact, were found with the side which was exposed to the storm completely scorched and burned, whereas the opposite side remained green and fresh."
8. ...suddenly it turned white outside. This whiteness definitely was not fog. I would say it appeared to be giving off a light of its own."
9. The beautiful electric blue light that was around the tornado was something to see, and balls of orange and lightning came from the cone point of the tornado."
10. The most interesting thing I remember is a surface glow -some three or four feet deep -- rolling noise, etc."

If a researcher had never heard of a tornado, and were asked to compare the eyewitness accounts of tornadoes (such as these) with those concerning UFOs, he would probably find the tornado reports to be more fantastic and incredible. Luminous tornado clouds with no funnels to the ground are possible causes of several UFO reports.

Dust Devil Electricity

During the heat of the day, the air temperature is high at the desert floor but decreases rapidly with height. At some critical temperature gradient (called the autoconvective lapse rate) violent upward convection of heated air occurs. Under certain desert conditions, the upward convection may be rather intense in small areas.

Rapidly rising air is replaced by cooler air which flows inward horizontally and asymmetrically, thereby creating a vertical vortex funnel. Such a desert vortex made visible by dust and sand particles, is known as a dust devil. Unlike the tornado, however, the dust devil begins from the ground and rises upward. Although it can sometimes blow a man over, it is much less powerful than a tornado.

Recent measurements indicate that strong electric fields are generated by dust devils. The precise nature of the charge separation process is not understood, but in this case at least, the electrical effects are almost certainly the result of convective motions and particle interactions.

Luminescent effects of dust devils have never been reported and would be extremely difficult to detect in the daytime. Since dust devils do not occur at night when the desert floor is cooler than the air above, this phenomenon can not explain UFOs reported at night.

Volcano Lightning

Undersea volcanic eruptions began on the morning of 14 November 1963, only 23 km from the southern coast of Iceland, where the water depth was 130 m. Within 10 days an island was created which was nearly 1 km long and 100 m above sea level. Motion pictures showed clouds rising vertically at 12 m/sec to an altitude of 9 km. The cloud of 1 December contained intense, almost continuous light, presumably the result of large dust particles and perhaps electret effects of sulfur.

Aircraft flights through the volcanic cloud were made during periods of no lightning. Large electric fields were measured, sometimes exceeding 11,000 volt/m.

The production of lightning by volcanos is of considerable interest for atmospheric electricity. Nevertheless, there is no evident relation between volcano lightning and UFO reports.

Earthquake-Associated Sky Luminescence

Intense electrical activity has often been reported prior to, during, and after earthquakes. Unusual luminescent phenomena seen in the sky have been classified into categories:

1. indefinite instantaneous illumination:
   1. lightning (and brightenings),
   2. sparks or sprinkles of light,
   3. thin luminous stripes or streamers;
2. well-defined and mobile luminous masses:
   1. fireballs (ball lightning),
   2. columns of fire (vertical),
   3. beams of fire (presumably horizontal or oblique),
   4. luminous funnels;
3. bright flames and emanations:
   1. flames,
   2. little flames,
   3. many sparks,
   4. luminous vapor;
4. phosphorescence of sky and clouds:
   1. diffused light in the sky,
   2. luminous clouds.

The classification is somewhat ambiguous, but is rather descriptive of luminous events associated with earthquakes.

The earliest description of such phenomena was given by Tacitus, who describes the earthquake of the Achaian cities in 373 B.C.E. Japanese records describe luminous effects during many severe earthquakes. In the Kamakura Earthquake of 1257, bluish flames were seen to emerge from fissures opened in the ground.

Flying luminous objects are mentioned in connection with the earthquake at Yedo (Tokyo) during the winter of 1672. A fireball resembling a paper-lantern was seen flying through the sky toward the east. During the Tosa earthquake of 1698, a number of fireballs shaped like wheels were seen flying in different directions. In the case of the Great Genroku Earthquake of 31 December 1730 in Tokaido, luminous "bodies" and luminous "air" were reported during the nights preceding the day of severest shock. Afterwards a kind of luminosity resembling sheet lightning was observed for about 20 days, even when there were no clouds in the sky. One record of the Shinano Earthquake of 1847 states: "Under the dark sky, a fiery cloud appeared in the direction of Mt. Izuna. It was seen to make a whirling motion and then disappeared. Immediately afterward, a roaring sound was heard, followed by severe earthquakes." In Kyoto in August, 1830, it is reported that during the night preceding the earthquake luminous phenomena were seen in the whole sky; at times, illumination emitted from the ground was comparable in brightness to daylight. In the Kwanto Earthquake of 1 September 1923, a staff member of the Central Meteorological Observatory saw a kind of stationary fireball in the sky of Tokyo.

The earthquake at Izu, 26 November 1930, was studied in detail for associated atmospheric luminescence. Many reports of sightings were obtained. The day prior to the quake, at 4 p.m., a number of fishermen observed a spherical luminous body to the west of Mt. Amagi, which moved northwest at considerable speed. Fireballs (ball lightning) and luminous clouds were repeatedly observed. A funnel-shaped light resembling a searchlight was also seen. Most witnesses reported pale blue or white illumination, but others reported reddish or orange colors.

That large electrical potentials can be created by the slippage or shearing of rocks is not surprising. Nevertheless, associated ball lightning and luminous clouds are of significance to this study. Of possible importance is the use of electrical measurements to provide some advance warning of an impending earthquake.

Mountaintop Electricity

Mountains are sharp projections which rise from the conducting surface of the earth. The electrical potential of a mountain is essentially equal to that of the surrounding lowlands. Consequently, when an electric field is set up between cloud and ground, the potential gradient (or electric field strength) reaches a maximum between the mountaintop and the overlying clouds.

The large potential gradient which often exists on a mountaintop may give rise to a number of events related to coronal discharge.

Physiological effects of large electric fields are frequently reported by mountaineers. Many of these effects are also occasionally reported in connection with UFOs. In this section we summarize eyewitness reports from mountaintops.

1. A graduate student of the University of Colorado was climbing Chimborazo, a high and isolated mountain in Ecuador. The summit is a large flat plateau 400 meters in diameter and 6266 meters above sea level. He and a companion left their camp at 5700 meters on the matin du 1er Mars 1968. At 10 a.m. clouds started forming at the peak, and a small amount of graupel began to fall. When they reached the summit, between 2 and 2:30 p.m., there was considerable cloudiness. Just as they were about to take the traditional photograph of conquest, the graupel began to fall more heavily. Suddenly they felt an odd sensation about their heads, described as mild electric shocks and crackling and buzzing sounds. Their aluminum glacier goggles began to vibrate, and their hair stood on end. The climbers dived into the snow and waited. Thunder was heard in the distance. They found that whenever they raised their heads off the ground, the electrical effects recurred. It seemed as if there were an oppressive layer 50 cm above the surface. After waiting half an hour, the climbers crawled off the peak on their bellies. They proceeded in this manner for an hour and a half, 400 meters across the plateau and down the slope. After descending 60 meters, they found they could stand up. By this time the fall of graupel and the sounds of thunder had ceased.
   During the 1870's and 1880's, the Harvard College Observatory maintained a meteorological station at the top of Pike's Peak. The journal of this expedition makes fascinating reading:
2. 16 July 1874. A very severe thunderstorm passed over the summit between 1 and 3 p.m., accompanied by mixed rain and hail. Sharp flashes and reports came through the lightning arrester, to the terror of several lady visitors; outside the building the electric effects were still more startling. The strange crackling of the hail, mentioned before, was again heard, and at the same time the observer's whiskers became strongly electrified and repellent, and gave quite audible hissing sounds. In spite of the cap worn, the observer's scalp appeared to be pricked with hundreds of red hot needles, and a burning sensation was felt on face and hands. Silent lightning was seen in all directions in the evening, and ground-currents passed incessantly through the arrester.
3. 21 July 1874. Not only did the constant crackling of the fallen hail indicate the highly electrified state of the summit, but from the very rocks proceeded a peculiar chattering noise, as if they were shaken by subterranean convulsions.
4. 25 May 1876. At 6 p.m. continued thunder was heard overhead and southeast of the peak. The arrester was continually making the usual crackling noise. About this time, while outdoors, the observer heard a peculiar "singing" at two or three places on the wire very similar to that of crickets. When the observer approached near one of these places the sound would cease, but would recommence as soon as he withdrew two or three feet distant.
5. 18 August 1876. During the evening the most curiously beautiful phenomenon ever seen by the observer was witnessed, in company with the assistant and four visitors. Mention has been made in journal of 25 May and 13 July of a peculiar "singing" or rather "sizzing" noise on the wire, but on those occasions it occurred in the daytime. Tonight it was heard again, but the line for an eighth of a mile (200 in) was distinctly outlined in brilliant light, which was thrown out from the wire in beautiful scintillations. Near us we could observe these little jets of flame very plainly. They were invariably in the shape of a quadrant, and the rays concentrated at the surface of the line in a small mass about The size of a currant, which had a bluish tinge. These little quadrants of light were constantly jumping from one point to another of the line, now pointing in one direction, and again in another. There was no heat to the light, and when the wire was touched, only the slightest tingling sensation was felt. Not only was the wire outlined in this manner, but every exposed metallic point and surface was similarly tipped or covered. The anemometer cups appeared as four balls of fire revolving slowly round a common center; the wind vane was outlined with the same phosphorescent light, and one of the visitors was very much alarmed by sparks which were plainly visible in his hair, though none appeared in the others'. At the time of the phenomenon snow was falling, and it has been previously noticed that the "singing" noise is never heard except when the atmosphere is very damp, and rain, hail, or snow is falling.
6. 16 June 1879. (During afternoon). One of those electric storms peculiar and common to Pike's Peak prevailed. A queer hissing sound issued from the telegraph line, the wind-vane post, and another post standing in a deep snow drift near by. Observer stepped out to view the phenomenon, but was not standing in the snow drift long, when the same buzz started from the top of his head; his hair became restless, and feeling a strange creeping sensation all over his body, he made quick steps for the station.
7. 10 July 1879. At 5 p.m. the hail turned to snow, and ceased at 5:30 p.m., the wind being gentle throughout. On stepping to the door at 6 p.m., observer states that he felt a peculiar sensation about the whole body, similar to that of an awakening limb after being benumbed; that his hair stood straight out from his head, and seemed to produce a peculiar "singing" noise like that of burning evergreens; the telegraph line and all metallic instruments producing a noise like that of swarming bees. When he put on his hat, the prickly sensation became so intense that he was compelled to remove it, his forehead smarting as though is had been burned for fully three hours later. At 7 p.m. the electric storm had ceased.

With the exception of tornado situations described earlier (where heat is also present), it is not likely that electrical sensations are anywhere more intense than on mountaintops. UFO reports sometimes indicate creepy, crawling sensations, much less pronounced, however, than those experienced by mountaineers.

Meteor Ionization and Meteor Sounds

A meteor is a streak of light produced by the interaction with the atmosphere of a solid particle (or meteoroid) from interplanetary space. Most meteoroids, particularly those that appear on schedule during certain times of the year, are probably dust balls which follow the orbit of a comet. When they enter the atmosphere they produce short-lived streaks of light commonly known as shooting stars.

A fireball or bolide (Greek for javelin) is a meteor with a luminosity that equals or exceeds that of the brightest planets (apparent magnitude -5). A solid object called a meteorite may be deposited on the earth's surface after a bolide, but never after scheduled meteor showers. The appearance of a bolide is random, and not correlated either in space or in time with comet orbits and the usual meteor showers. Bolides are believed to be caused by solid fragments from the asteroid belt, whereas the scheduled meteors are caused by dust balls from cometary orbits.

When a meteoroid passes through the upper atmosphere, a shock wave is generated, accompanied by intense heating of the surrounding air and the meteoroid surfaces. Atoms which boil off the meteoroid surface possess thermal speeds of about 1 km/sec and directed velocities of up to 72 km/sec. They collide with surrounding air molecules, and create an envelope of ionization and excitation. A meteorite only a few tens of centimeters wide may be surrounded by an ionized sheath of gas some tens of meters or more in diameter. De-excitation and recombination processes give rise to the long visible trail behind the meteoroid. Meteor trails are visible at altitudes between 110 and 70 km.

The brightest bolides can cast shadows over a radius of 650 km. To be as bright as the full moon, meteoroids of at least 100 kg are required. About 1500 meteoroids enter the earth's atmosphere each year, each with a mass greater than 100 kg.

The visual appearance of a bolide differs considerably from that of a shooting star. Vivid colors and color changes are common. Bolides have been seen to break apart, with fragments circling slowly on the way down or flying in a line or in an apparent formation. The trajectory of a bolide can appear almost horizontal to the observer. Because of the extreme brightness and the large diameter of the ionization envelope, distances to bolides are always underestimated, particularly if it should flare up toward the end of the descent. Odors of brimstone near the impact point have also been reported.

Meteor trains associated with bolides sometimes remain luminescent for an hour or so. Such a train may appear as a glowing column about one kilometer in diameter. The mechanism which allows certain meteor trains to glow for so long a time is not known. Radar trails of ordinary meteors last only 0.5 sec. Spectral analysis of glowing meteor trails reveals many bright emission lines from excited air atoms. Radiation from the hot surface of a meteoroid has also been detected on rare occasions. These emission lines reveal only common elements (such as iron, sodium, magnesium, and other minerals), implying a chemical composition similar to the earth and to the asteroids. During the day, a bolide train is seen as a pillar of dust at lower altitudes rather than as a glowing column in the upper atmosphere.

Some minutes after exceptionally bright bolides, some witnesses have heard sounds described as thunder, the boom of a cannon, rifle or pistol fire, etc. These sounds are produced by the fall and deceleration of a massive meteorite or of several fragments.

There are also a significant number of reports concerning sounds heard while the bolide was still descending from the sky, perhaps a hundred kilometers above the ground. These sounds are described as hissing, swishing, whizzing, whirring, buzzing, and crackling, and are attributed to bolides with an average apparent magnitude of -13 (about the brightness of the full moon). Such noises could not have propagated all the way from the meteorite, since sound travels too slowly.

At one time it was believed that people who observed bolides imagined the sounds, as a psychological association with noise from sparklers and other fireworks. Meteor sounds are now regarded as physical effects. On several occasions the observer first heard the noise and then looked upward to seek the cause. (Similar noise has also been reported during times of auroral activity.)

One hypothesis is that low frequency electromagnetic radiation is emitted by bright bolides and detected by human sense organs. Human subjects exposed to radar beams of low intensity have perceived sensations of sound described as buzzing, clicking, hissing, or knocking, depending on the transmitter characteristics. A pulse-modulated signal with a peak electromagnetic radiation flux of 4 watt/m² at the observer was perceived as sound by subjects whose audible hearing was good above 5 kHz. If the background noise exceeded 90 decibels, the radio frequency sound was masked, but earplugs improved the reception.

During the fall of one of the largest bolides, near Sikhote-Alin, near Vladiovostok (USSR), an electrician on a telephone pole received a strong electric shock from disconnected wires at the instant the bolide became visible. The shock may have been due to other causes, but the possibility of strong electromagnetic effects is not ruled out.

At present, measurements made during smaller meteor events (of the dust ball variety) give no indication of significant radio emission. Magnetic effects are insignificant.

Another conjecture is that atomic collisions in the vicinity of a meteorite bring about a separation of charge along the ionization trail of the bolide. For coronal discharge effects to occur at ground level, however, the bolide would have to separate many thousands (or even tens of thousands) of coulombs about 30 km. along its ionization trail. Such a process seems unlikely.

The noises which appear simultaneously with the bolide are not understood. If strong electrical fields accompany a bolide, other effects such as lightning or ball lightning may occur. Both lightning and ball lightning have occasionally been reported in clear non-stormy weather. There are also several reports of large chunks of ice falling out of cloudless skies. They are not believed to have fallen from aircraft. The ice chunks may arise from electrical effects of bolides, or (more probably) may be the meteorites themselves.

Micrométéorites d'antimatière

Théories des plamas pour les ovnis

2 articles et un livre à succès ont été écrits sur les interprétations d'ovnis comme des plasmas P. J. Klass. Klass fut marqué par des rapports d'ovnis en relation étroite avec des lignes de haute tension près de Exeter, New Hampshire. De nombreux livres fameux considèrent que les ovnis sont des vaisseaux spatiaux extraterrestres qui survolent nos lignes de haute tension pour faire le plein. Klass pense que certains ovnis sont une forme inhabituelle de décharge coronaire semblable au feu de Saint Elme.

Dans son 1er article, la foudre en boule est supposée être la manifestation d'une décharge coronaire extrême. Klass met en avant que la foudre en boule et les ovnis d'Exeter se comparent assez bien étant donné leurs couleur, forme, son, dynamique, durée de vie, et taille. D'après ces rapports, les diamètres des ovnis variaient depuis la taille d'un ballon de basket jusqu'à 60 m. Cet écarte de taille peut être du à la difficulté d'estimer des distances en plein nuit sans points de référence visibles. Exeter est suffisamment proche de la mer pour que le sel se forme sur les lignes de haute tension et il y eut très peu de pluie cet été-là pour nettoyer le sel, fournissant ainsi des points une décharge coronaire pouvait intervenir.

Des critiques sont :

1. que les autres villes de gardes-côtes avec des lignes de haute tension n'ont pas signalé d'activités d'ovnis durant la période sèche, et
2. la luminosité, bien que près des fils, se trouvait parfois éloignée d'une certaine distance angulaire.

Klass examina également d'autres signalements d'ovnis dont ceux vu à des altitudes d'avions. Dans son 2nd article, qui se préoccupe du problème ovni en général il affirme que la foudre en boule peut intervenir de de nombreuses situations, et par conséquent être la cause de nombreuses observations d'ovnis inhabituelles. De nombreux aspects de la foudre en boule et ka création en laboratoire de plasmas lumineux par décharges de micro-ondes et gaz sont brièvement discutés. Klass avance que les blobs de plasma auraient les mêmes caractéristiques et causeraient les mêmes effets que ceux parfois attribués aux ovnis, y compris les disparitions soudaines (parfois explosives), les manœuvres près des appareils, les accélerations rapid, les automobiles calées, la chaleur, les sensations de prickling, les yeux irrités, etc. Il discute l'observation d'un ovni via des lunettes de soleil Polaroid et le signalement d'un compas magnétique agité.

Le livre, OVNIs Identifiés, est une version étendue de 2 articles, et contient le contexte de l'enquête de l'auteur. Il discute de la foudre en boule, la comportement et l'apparence des ovnis, les indices radar et photographiques, les diverses réactions à ses articles, et le récit d'un couple déclarant avoir été maintenus prisonniers dans un ovni. Le livre ne tente pas de résumer quelque des principes fondamentaux de l'électricité atmosphérique, la physicique des plasmas, ou la dynamique atmosphérique.

Au sujet des signalements d'automobiles callées près des ovnis, Klass écrit :

Parce qu'un plasma contient un nuage de particules électrifiées, il ne fait aucun doute que si une batterie d'auto était enveloppée par un tel plasma la batterie sera court-circuitée. Mais il est difficile d'expliquer comment un plasma-ovni pourraient avoir accès à la batterie de la voiture dans le bloc moteur sans d'abord dissiper son énergie dans la corps métallique de la voiture. Une autre explication possible est basée sur le fait qu'une charge électrique au voisinage d'une surface conductrice, telle que l'habitacle d'une voiture, crée une image miroir d'elle-même sur le côté opposé de la surface conductrice. L'implication est ici erronnée : la charge image discutée en théorie électrique n'est pas une véritable charge de l'autre côté de l'écran métallique, mais une fiction mathématique utilisée pour décrire l'altération du champ électrique par redistribution des charges électriques sur l'écran métallique.

Les défaillances prétendues d'automobile sont discutées en Section 3, Chapitre 4 de ce rapport, et ont été omises ici à dessein. Cependant, quelques remarques may be in order. Comme le fait remarquer Klass, some motorists ont signalé que les phares comme le moteur défaillaient. D'autres ont signalé que seul le moteur ou seuls les phares défaillaient. Souvent les voitures de police ont pris en chasse des ovnis sur des dizaines de km donc la défaillance de moteur ne survient pas tout le temps. De plus, aucun motifs magnétiques inhabituels n'ont jusqu'ici été détectés dans les corps d'autos.

Lorsque le radar était développé en secret par la RAF avant le London Blitz (2nde guerre mondiale), certaines des personnes locales de Burnhamon-Crouch étaient convaincues que les mâts mystérieux récemment élevés avaient arrêtés les automobiles qui passaient. Vraissemblablement lorsque le but du radar devint connu, les voitures ne calaient plus.

En plus de la foudre en boule et de la décharge coronaire, il suggère également des nuages de tornade sans entounnoir jusqu'au sol, de la luminescence générée durant les tempètes de neige, des vortex de poussière en rotation, et de petits crystaux de glace chargés. Une autre de ses idées est que parfois un appareil hautement chargé puisse diffuser des ions dans un grand vortex [wingtip]. Le vortex reste lumineux pendant un moment, pour être rencontré peu après par un autre appareil. Bien que les effets coronaires interviennent sur les surfaces d'appareils, il est peu probable qu'une foudre globulaire puisse se détacher d'un appareil et rester lumineuse pendant plus de quelques secondes.

Conférence ovni sur les plasmas

Les 27 et 28 Octobre 1967, plusieurs physiciens experts en physique des plasmas ou électricité atmosphérique se rencontrèrent à Boulder (Colorado), pour discuter du problème des ovnis avec les membres de l'équipe de ce projet. Les participants à la conférence des ovnis plasma furent :

• Marx Brook : Institut de Mining and Technology du Nouveau-Mexique
• Keith A. Brueckner : Université de Californie (San Diego)
• Nicholas C. Christofilos : Université de Californie (Livermore)
• Ronald T. H. Collis : Institut de Recherche de Stanford
• Edmond M. Dewan : Laboratoires de Recherche de l'Air Force de Cambridge
• Herman W. Hoerlin : Laboratoires Scientifiques de Los Alamos
• Bernd T. Matthias : Université de Californie (San Diego)
• Arnold T. Nordsieck : Santa Barbara, Californie
• Marshall N. Rosenbluth : Centre de Recherche James Forrestal
• John H. Taylor : Université de Californie (San Diego)
• UFO Study Members

Various aspects of atmospheric electricity were reviewed, such as ball lightning, and tornado and earthquake luminescence. Unusual UFO reports were presented for discussion. These included a taped report by a B-47 pilot whose plane was paced for a considerable time by a glowing object. Ground radar reported a pacing blip which appeared to be 16 km from the aircraft. After review the unanimous conclusion was that the object was not a plasma or an electrical luminosity produced by the atmosphere.

Participants with a background in theoretical or experimental plasma physics felt that containment of plasma by magnetic fields is not likely under atmospheric conditions for more than a second or so. One participant listed the characteristics that would be expected to accompany a large plasma. These are

1. thermal emission,
2. production of ozone and odor of N₂O
3. convective air motions,
4. electrical and acoustic noise,
5. unusual meteorological conditions.

Another plasma physicist noted that a plasma explanation of certain UFO reports would require an energy density large enough to cause an explosive decay. Atmospheric physicists, however, remarked that several reports of ball lightning do indicate unusually high energy densities.

All participants agreed that the UFO cases presented contained insufficient data for a definitive scientific conclusion.

Références et notes

Sections 0, 1, 2

A review of atmospheric electricity, which contains about 1000 references to previous work in the field, is:

1. Atmospheric Electricity, (2nd edition), J. Alan Chalmers: Pergamon Press, 1967.

A readable introduction to plasma physics is:

2. Elementary Plasma Physics, Lev. A. Arzimovich: Blaisdell Publ., 1965 (Russian edition, 1963).

An extremely engrossing scientific detective story is:

3. Cosmic Rays, Bruno Rossi: McGraw-Hill Books, 1964.

For the sun and the earth, the following articles are useful for background:

4. Our Sun, (revised edition), Donald H. Menzel: Harvard Univ. Press, 1959.
5. Sunspots, R.J. Bray and R.E. Loughhead: John Wiley & Sons, 1965.
6. Solar Flares, Henry J. Smitix and Elske V.P. Smith: Macmillan Co., 1963.
7. "Magnetic Fields on the Quiet Sun", William C. Livingston: Scientific American, November, 1966.
8. "Magnetosphere", Laurence J. Cahill, Jr.: Scientific American, March, 1965.
9. "Aurora", Syun-Ichi Akasofu: Scientific American, December, 1965.
10. Keoeeit, The Story of the Aurora Borealis, William Petrie: Pergamon Press, 1963.
11. Auroral Phenomena, Martin Walt (editor): Stanford Univ. Press, 1965.
12. The Earth's Magnetism (2nd edition), Sydney Chapman: Methuen, London, 1951.

Radio propagation through the ionosphere and plasma technology are discussed in:

13. Radio Amateur's Handbook: American Radio Relay League, Newington, Connecticut, 1968.
14. "Progress Toward Fusion Power", T.K. Fowler and R.F. Post: Scientific American, December, 1966.
15. "Shock Waves and High Temperature", Malcolm McChesney: Scientific American, February, 1963.
16. "Electrical Propulsion in Space", Gabriel Giannini: Scientific American, March, 1961.
17. "Electric Propulsion", Robert G. Jahn: American Scientist, vol. 52, p. 207, 1964.

Section 3

1. Exploring the Atmosphere, G.M.B. Dobson: Clarendon Press Oxford, 1963.
2. The Science of Weather, John A. Day: Addison Wesley Books, 1966.
3. Introduction to the Atmosphere, Herbert Riehl: McGraw-Hill, 1965.
4. Meteorology, William L. Donn: McGraw-Hill, 1965.
5. Weather, Philip D. Thompson and Robert O'Brien: Time-Life Books, 1965.

An advanced treatise is:

6. Physics of the Atmosphere, P.N. Tverskoi: Israel Program for Scientific Translations, Jerusalem, 1965 (Russian edition, 1962) (NASA TT F-288, U.S. Dept. of Commerce).

Sections 4, 5, 6

In addition to Chalmer's book cited earlier, detailed treatises are:

1. Electricity of the Free Atmosphere, I.M. Imyanitov and E.V. Chubarina: Israel Program for Scientific Translations, Jerusalem, 1967. (Russian edition, 1965) (NASA 'FT F-425, U.S. Dept. of Commerce).
2. Physics of Lightning, D.J. Malan: English Univ. Press, 1963.

Temperature in a lightning stroke is discussed in:

3. "Pressure Pulse from a Lightning Stroke", E.L. Hill, and J.D. Robb: Journal of Geophysical Research, vol. 73, p. 1883, 1968.

An elementary account of lightning is:

4. The Lightning Book, Peter E. Viemeister: Doubleday, 1961.

A recent theory of charge separation in thunderstorms is:

5. "The Role of Particle Interactions in the Distribution of Electricity in Thunderstorms", J.D. Sartor: Journal of Atmospheric Sciences, vol. 24, p. 601, 1967.

Section 7

Surveys of ball lightning are:

1. Preliminary Report on Ball Lightning, J. Rand McNally, Jr.: Second Annual Meeting, Div. of Plasma Phys., Amer. Phys. Soc., Gatlinburg, Tenn. Nov. 2-5, 1960.
2. Ball Lightning Characteristics, Warren D. Rayle: NASA TN D-3188, January, 1966.
3. Ball Lightning, James Dale Barry: Master's Thesis, California State College, 1966.
4. "Ball Lightning", J. Dale Barry: Journal of Atmospheric and Terrestrial Physics, vol. 29, p. 1095, 1967.

Bibliographies of earlier ball lightning work are contained in reference #3 above and in:

5. Ball Lightning Bibliography 1950-1960: Science and Technology Division, Library of Congress, 1961.
6. Ball Lightning (A Collection of Soviet Research in English Translation), Donald J. Ritchie (editor): Consultants Bureau, New York, 1961.

A theory based on standing microwave patterns is given in:

7. "The Nature of Ball Lightning", P.L. Kapitsa: in Ball Lightning, Consultants Bureau, N.Y., 1961 (Doklady Akademii Nauk SSSR, vol. 101, p. 245, 1955).

A theory based on external d-c electric fields in given in:

8. "Ball Lightning", David Einkelstein and Julio Rubinstein: Physical Review, vol. 135, p. A390, 1964.
9. "A Theory of Ball Lightning", Martin A. Uman and Carl W. Helstrom: Journal of Geophysical Research, vol. 71, P. 1975, 1966.

Theories based on magnetic containment are given by:

10. "Ball Lightning and Self-Containing Electromagnetic Fields", Philip O. Johnson: American Journal of Physics, vol. 33, p. 119, 1965.
11. "Ball Lightning", E.R. Wooding: Nature, vol. 199, p. 272, 1963.
12. "On Magnetohydrodynamical Equilibrium Configurations", V.D. Shafranov: in Ball Lightning, Consultants Bureau, N.Y., 1961 (Zhurnal Eksperimentalnoi i Teoreticheskoi Fiziki, vol. 37, p. 224, 1959).
13. "Magneto-Vortex Rings", Yu. P. Ladikov: in Ball Lightning, Consultants Bureau, N.Y., 1961 (Izvestiya Akademii Nauk SSSR, Mekhanika i Mashinostroyenie, No. 4, p. 7, July-Aug., 1960).

A theory of ball lightning as a miniature thundercloud is given in:

14. "Ball Lightning as a Physical Phenomenon", E.L. Hill: Journal of Geophysical Research, vol. 65, p. 1947, 1960.

The creation of ball lightning by man-made devices is discussed in:

15. "Ball Lightning and Plasmoids", Paul A. Silberg: Journal of Geophysical Research, vol. 67, p. 4941, 1962.

Ball lightning as burning hydrocarbon is discussed in:

16. "Laboratory Ball Lightning", J. Dale Barry: Journal of Terrestrial Physics, vol. 30, P. 313, 1968.

The above list of ideas on the nature of ball lightning is far from exhaustive. A skeptical view of ball lightning theories is given in:

17. "Attempted Explanations of Ball Lightning", Edmond M. Dewan: Physical Sciences Research Paper #67, AFCRL-64-927, November, 1964.

An elementary review of ball lightning is:

18. "Ball Lightning", H.W. Lewis: Scientific American, March, 1963.

The first eyewitness account presented in this review is found in:

19. "The Nature of Ball Lightning", G.I. Kogan-Beletskii: in Ball Lightning, Consultants Bureau, N.Y., 1961 (Prioroda, No. 4, p. 71, 1957).

Eyewitness accounts 2, 3, 5, 6, 7, and many others even more incredible are found in:

20. Eyewitness Accounts of Kugelblitz, Edmond M. Dewan: CRD-25, (Air Force Cambridge Research Laboratories) March, 1964.

Account 4 concerns a photograph taken by Robert J. Childerhose of the RCAF. The description is found in the book by Klass, which is cited below.

The strange case in St. Petersburg, Florida is discussed in:

21. "Theory of the Lightning Balls and Its Application to the Atmospheric Phenomenon Called 'Flying Saucers'", Carl Benedicks: Arkiv for Geofysik (Sweden), vol. 2, p. 1, 1954.

Section 8

An advanced treatise, primarily concerned with laboratory experiments, is:

1. Electrical Coronas (Their Basic Physical Mechanisms), Leonard B. Loeb: Univ. of California Press, 1965. See also:
2. "High Voltage Transmissions," L.O. Barthold and H.G. Pfeiffer: Scientific American, May, 1964.
3. "Corona Chemistry", John A. Coffman and William R. Browne: Scientific American, June, 1965.

Section 9

See reference #3 in ball lightning, and

1. The Nature of Light and Colour in the Open Air, M. Minnaert: Dover Publ., 1954.

Section 10

1. Tornadoes of the United States, Snowden D. Flora: Univ. of Oklahoma Press, 1954.
2. "Tornadoes", Morris Tepper: Scientific American, May, 1958.
3. On the Mechanics of a Tornado, J.R. Fulks: National Severe Storms Project Report No. 4, U.S. Dept. of Commerce, February, 1962.
4. "Electrical Theory of Tornadoes", Bernard Vonnegut: Journal of Geophysical Research, vol. 65, p. 203, 1960.
5. "Tornadoes: Mechanism and Control", Stirling A. Colgate: Science, vol. 157, p. 1431, 1967.

Magnetic measurements near a tornado are reported in:

6. "Electric Currents Accompanying Tornado Activity", Marx Brook: Science, vol. 157, p. 1434, 1967.

The eyewitness reports used in this review came from a number of sources, and were collected in:

7. "Electromagnetic Phenomena in Tornadoes", Paul A. Silberg: Electronic Progress, Raytheon Company, Sept. - Oct., 1961.
8. "Dehydration and Burning Produced by the Tornado", P.A. Silberg: Journal of the Atmospheric Sciences, vol. 23, p. 202, 1966.
9. "Luminous Phenomena in Nocturnal Tornadoes", B. Vonnegut and James R. Weyer: Science, vol. 153, p. 1213, 1966.

Section 11

1. "The Electric Field of a Large Dust Devil", G.D. Freier: Journal of Geophysical Research, vol. 65, p. 3504, 1960.
2. "The Electric Field of a New Mexico Dust Devil", W.D. Crozier: Journal of Geophysical Research, vol. 69, p. 5427, 1964.

Section 12

1. "Whirlwinds Produced by the Eruption of Surtsey Volcano", Sigurdur Thorarinsson and Bernard Vonnegut: Bulletin American Meteorological Society, vol. 45, p. 440, 1964.
2. "Electricity in Volcanic Clouds", Robert Anderson et al.: Science, vol. 148, p. 1179, 1965.

Section 13

1. "On Luminous Phenomena Accompanying Earthquakes", Torahiko Terada: Bulletin of the Earthquake Research Institute, Tokyo Imperial University, vol. 9, p. 225, 1931.
2. "Raccolta e Classificazione di Fenomeni Luminosi Osservati nei Terremoti", Ignazio Galli: Bolletino della Societa Italiana, vol. 14, p. 221,1910.

For background

3. "Long Earthquake Waves", Jack Oliver: Scientific American, March, 1959.
4. "The Plastic Layers of the Earth's Mantle", Don L. Anderson: Scientific American, July, 1962.

Section 14

1. Personal communication from Thomas Bowen, Dept. of Anthropology, University of Colorado, 1968.
2. "Extract from Daily Journal, Summit of Pike's Peak, Colorado": Annals of the Observatory of Harvard College, vol. 22, p. 459, 1889.

Section 15

1. Meteors, Comets, and Meteorites, Gerald S. Hawkins: McGraw-Hill, 1964.
2. Meteorites, Fritz Heide: Univ. of Chicago Press, 1964 (German edition, 1957)
3. Out of the Sky (An Introduction to Meteoritics), H.H. Nininger: Dover Publ., 1952.
4. "Strange Sounds from the Sky", Mary F. Romig and Donald L. Lamar: Sky and Telescope, October, 1964.
5. Principles of Meteoritics, E.L. Krinov: Pergamon Press, 1960 (translated from Russian).
6. Giant Meteorites, E.L. Krinov: Pergamon Press, 1966 (translated from Russian).
7. Meteor Science and Engineering, D.W.R. McKinley: McGraw-Hill, 1961.
8. "Fossil Meteorite Craters", C.S. Beals: Scientific American, July, 1958.
9. "High Speed Impact", A.C. Charters: Scientific American, October, 1960.
10. "Note on Persistent Meteor Trails", Sydney Chapman: in The Airglow and the Aurorae, (Belfast Symposium, 1955), E.M. Armstrong and A. Dalgarno (editors), Pergamon Press, 1956.

Section 16

The description of the 1908 bolide is found in reference #6 above by Krinov. Evidence that anti-matter is not involved, is discussed in:

1. "Possible Anti-Matter Content of the Tunguska Meteor of 1908", Clyde Cowan, C.R. Alturi, and W.F. Libby: Nature, vol. 206, p. 861, 1965.
2. "Non-anti-matter Nature of the Tunguska Meteor", L. Marshall: Nature, vol. 212, p. 1226, 1966.

Anti-matter in the universe is discussed in:

3. "Anti-Matter", Geoffrey Burbidge and Fred Hoyle: Scientific American, April, 1958.
4. Worlds-Antiworlds, Hannes Alfven: W.H. Freeman and Co., 1966.
5. "Anti-Matter and Cosmology", Hannes Alfv4n: Scientific American, April, 1967.

Chemical radicals are discussed in:

6. "Frozen Free Radicals", Charles M. Herzfeld and Arnold M. Bass: Scientific American, March, 1957.
7. "Production and Reactions of Free Radicals in Outer Space", F. O. Rice: American Scientist, vol. 54, p. 158, 1966.

Also for background:

8. "Chemistry at High Velocities", Richard Wolfgang: Scientific American, January, 1966.

An alien spaceship theory is advocated in:

9. "Unidentified Flying Objects", Felix Y. Ziegel: Soviet Life, 1968-02.

Section 17

1. "Plasma Theory May Explain Many UFO's", Philip J. Klass: Aviation Week and Space Technology, p. 48, August 22, 1966.
2. "Many UFOs are Identified as Plasmas", Philip J. Klass: Aviation Week and Space Technology, p. 54, October 3, 1966.
3. UFOs Identified,. Philip J. Klass: Random House, 1968.

Stalled automobiles in connection with radar are mentioned in:

4. Full Circle (The Tactics of Air Fighting 1914-1964), Group Captain John E. Johnson: Ballantine Books, 1964.

Vortices created by aircraft are discussed in:

5. "Boundary Layer", Joseph J. Cornish III: Scientific American, August, 1954.
6. Shape and Flow, Ascher H. Shapiro: Doubleday Anchor Books, 1961.
7. Airman's Information Manual, Part I: Federal Aviation Administration, November, 1967.

Criticisms of Klass' ideas are found in:

8. UFOs: An International Scientific Problem, James E. McDonald: Astronautics Symposium, Canadian Aeronautics and Space Institute, Montreal) Canada, 12 March 1968.

Section 18

The difficulties involved in the magnetic confinement of a plasma are discussed in:

1. "Leakage Problems in Fusion Reactors", Francis F. Chen: Scientific American, July, 1967.

Section 19

In addition to the aspects of atmospheric electricity mentioned in this review, many other physical phenomena and psychological effects may be involved in many (if not all) sightings. For background reading in addition to Minnaert's book cited in Section 9:

1. Flying Saucers, Donald H. Menzel: Harvard Univ. Press, 1953.
2. The World of Flying Saucers, Donald H. Menzel et Lyle G. Boyd: Doubleday & Co., 1963.
3. "Afterimages", G .S. Brindley: Scientific American, October, 1963.
4. "Illusion of Movement", Paul A. Kolers: Scientific American, October, 1964.
5. "Texture and Visual Perception", Bela Julesz: Scientific American, February, 1965.
6. "Psychological Time", John Cohen: Scientific American, November, 1964.
7. "Aerial Migration of Insects", C.G. Johnson: Scientific American, December, 1963.
8. "Biological Luminescence", W.D. McElroy and H.H. Seliger: Scientific American, December, 1962.
9. Various Colorado newspapers, April 11, 1966.
10. The Elements Rage, Frank W. Lane: Chilton Books, 1965.