Ball Lightning - new info
Michel T. Talbot
name given to the mobile luminous spheres which have been observed
during thunderstorms. A typical ball lightning is about the size of an
orange or a grapefruit and has a lifetime of a few seconds. Compilations
of eye-witness reports of ball lightning have been published by
Brand(1923), Rodewald(1954), Dewan(1964), Silberg(1965), McNally(1966)
and Rayle(1967) among others. Visual sightings are often accompanied by
sound, odor, and permanent material damage, and hence it would appear
difficult to deny the reality of the phenomenon [as Humphreys(1936) has
done]. In a letter to the editor of the London Daily Mail, Morris(1936)
described an unusual incident in which a ball lightning caused a tub of
water to boil:
During a thunderstorm I saw a large, red hot ball come down from the
sky. It struck our house, cut the telephone wire, burnt the window
frame,and then buried itself in a tub of water which was underneath.
The water boiled for some minutes afterwards, but when it was cool
enough for me to search I could find nothing in it."
Photographs purported to be of ball lightning have been published by
Jensen(1933), Kuhn(1951), Wolf(1956), Davidov(1958), Jennings(1962), and
Muller-Hillebrand(1963). A phenomenon very similar to, if not identical
with, ball lightning has been reported to occur in submarines due to
discharge of a current about 150,000 amp direct current from a 260-volt
source across a circuit breaker(Silberg, 1962). In addition a number of
reports were received of ball-lightning-like phenomena being initiated
accidentally in high-power electrical equipment.
Ball lightning and St. Elmo's fire are sometimes confused. St. Elmo's
fire is a corona discharge from a pointed conducting object in a strong
electric field. Like ball lightning, St. Elmo's fire may assume a
spherical shape. Unlike ball lightning, St. Elmo's fire must remain
attached to a conductor, although it may exhibit some motion along the
conductor. Further, St. Elmo's fire can have a lifetime much greater
than the lifetime of the usual ball lightning.
From the many published ball lightning observations, it is possible to
compile a list of:
ball lightning characteristics
------------------------------
1. Occurrence
Most observations of ball lightning are made during thunderstorm activity.
Most, but not all, of thunderstorm-related ball lightning appear almost
simultaneously with a cloud-to-ground lightning discharge. These ball
lightnings appear within a few meters of the ground. Sometimes ball
lightnings are reported to occur near the ground in the absence of a
lightning discharge. Ball lightnings have also been observed to hang
in mid-air far above the ground and have been observed falling from a
cloud towards the ground.
2. Appearance
Ball lightnings are generally spherical, although other shapes have been
reported they are usually 0.1-0.2m in diameter, with reported diameters
ranging from 0.01-1.00m. Ball lightnings come in various colors, the most
common colors being red, orange, and yellow. Ball lightning are generally
not exceptionally bright, but can be seen clearly in daylight. They are
usually reported to maintain a relatively constant brightness and size
during their lifetimes, although ball lightnings which change in
brightness and size are not uncommon.
3. Lifetime
Ball lightnings generally have a lifetime of less than 5 seconds.
A small fraction of reports indicate a lifetime of over a minute.
4. Motion
Ball lightning usually move horizontally at a velocity of a few meters
per second. They may also remain motionless in mid-air or may descend
from a cloud towards the ground. They do not often rise, as would be
the case if they were spheres of hot air at atmospheric pressure in the
presence of only a gravitational force. Many reports describe ball
lightning which appear to spin or rotate as they move. Ball lightnings
are sometimes reported to bounce off solid objects, typically the ground.
5. Heat, sound and odor
Rarely do observers of ball lightning report the sensation of heat.
However, accounts of ball lightning which burned barns and melted wires
do exist. One report found in McNally (1966) described a ball lightning
which hit a pond of water with a sound "as if putting a red hot piece of
iron into the water." Sometimes ball lightnings are reported to emit a
hissing sound. Many observers report a distinctive odor accompanying
ball lightning. The odor is usually described as sharp and repugnant,
resembling ozone, burning sulphur, or nitric oxide.
6. Attraction to objects and enclosures
Ball lightnings are often reported to be attracted to metallic objects
such as wire fences or telephone lines. When attached to metallic
objects, they generally move along those objects. Some or all these
observations may refer to a type of St. Elmo's fire. Ball lightnings
often enter houses through screens or chimneys. Sometimes they are
reported to enter houses through glass window panes. They are also
reported to originate within buildings, on occasion from telephones.
Ball lightnings can exist in an all-metal enclosure such as the interior
of an airplane (Uman, 1968).
7. Demise
Ball lightnings decay in one of two modes, either silently or
explosively. The explosive decay takes place rapidly and is accompanied
by a loud noise. The silent decay can take place either rapidly or
slowly. After the ball has decayed, it is sometimes reported that a
mist or residue remains. Occasionally a ball lightning has been
observed to break up into two or more smaller ball lightnings.
8. Types
There may be more than one type of ball lightning. For example, the
ball lightning that attaches to conductors may be different from the
free-floating ball lightning; and the ball lightning that appears near
ground may be different from the ball lightning that hangs high in the
air or the ball lightning that falls out of a cloud
No theory of ball lightning exists which can account for both the degree
of mobility that the ball exhibits and for the fact that it does not rise.
Thus, despite the numerous theoretical models proposed for the phenomenon,
the mechanisms which cause the ball lighting remain unknown. All ball
lightning theories fall into one of two general classes:
Ball Lightning Theories
-----------------------
I. Energy source is stored within the ball (Internally powered) and
E. Energy source is outside the ball (Externally powered)
Internally powered models
-------------------------
I1 The ball lightning is gas or air behaving in a "unusual" way. It has
been suggested that the ball lightning is slowly burning gas, is the
radiation from long-lived metastable states of air particles or from
particles which absorb energy from the metastables, is due to chemical
reactions involving dust, soots, etc., and so on.
I2 Ball lightning is a sphere of heated air at atmospheric pressure.
Uman and Lowke (1968) have calculated the temporal and spatial
characteristics of a sphere of hot air. It was found that for a sphere
of about 0.2m in diameter, the cooling rate was about 100K/sec in the
temperature range near 3000K and that the sphere maintained an
essentially constant radius during the cooling process. Unfortunately,
the relatively small cooling rate does not lead to a relatively
constant ball brightness.
I3 Ball lightning is a very high density plasma (with electron density
25 -3
of 10 m ) which exhibits quantum mechanical properties
characteristic of the solid state (Neugebauer, 1937)
I4 Ball lightning is due to one of several suggested configurations of
closed loop current flow contained by it's own magnetic field.
Finkelstein and Rubinstein(1964) have shown that plasma containment
of this type is not possible under normal conditions in air.
I5 Ball lightning is due to some sort of air vortex (like a smoke ring)
providing containment for luminous gases.
I6 Ball lightning is a microwave radiation field contained within a thin
spherical shell of plasma (Dawson and Jones, 1968).
Externally powered models (External Power Sources)
-------------------------
E1 High-frequency >100MHz EMF
--------------------------
Cerrillo(1943) and Kapitza(1955) proposed that focused RF energy from
the thundercloud could create and maintain a ball lightning. The high
electric fields necessary to effect this mechanism have never been
observed in thunderstorms.
E2 Steady current flow from cloud to ground
----------------------------------------
Finklestein and Rubinstein(1964) and Uman and Helstrom(1966) have
suggested that a steady current flowing from cloud to ground would
contract in cross section in a region of high conductivity (the ball)
and that the increased energy input due to the constriction of current
could maintain the ball. This type of theory cannot account for the
existence of ball lightning inside structures, particularly inside
metal structures.
E3 Focused Cosmic Ray Particles?
-----------------------------
Arabadzhi(1957) has suggested that radioactive cosmic-ray particles
could be focused by the electric fields of the thunderstorm so that
they would create an air discharge at one point in space.
Ball Lightning References (94 04 22)
=========================
all this text was from Appendix C in the book:
Uman, M.A. "Lightning", pp243-248 (Dover, 1968)
Eye Witness Reports
-------------------
Brand, W.: "Der Kugelblitz," Grand, Hamburg, Germany, 1923
Arthur C. Clarke's "Mysterious Worlds"pp301-307(1980), Fontana/Collins
Dewan, E.M.: Eyewitness Accounts of Kugelblitz, Microwave Physics Lab, Air
Force Cambridge Res. Lab., CRD-125, March, 1964.
Humphreys, W.J.: Ball Lightning, Proc. Am. Phil. Soc. 76:613-626(1936)
McNally, J. Rand, Jr.: Preliminary Report on Ball Lightning, Oak Ridge
National Laboratory, ORNL-3938, UC-34-Phys,. May, 1966
Morris, W.: A Thunderstorm Mystery, letters to the editor of Daily Mail
of London, Nov. 5, 1936
Rayle, W.D.: Ball Lightning Characteristics, NASA Tech. Note D-3188(Jan,67)
Rodewald, M.: Kugelblitzbeobachtungen, Z. Meteorol., 8:27-29(1954)
Silberg, P.A.: A Review of Ball Lightning, in S.C. Corondi(ed.), "Problems
of Atmospheric and Space Electricity", pp.436-454, American Elsevier
Publishing Company, New York, 1965
Photographs
-----------
Arthur C. Clarke's "Mysterious Worlds" p302, Fontana/Collins
Davidov, B., Rare Photograph of Ball Lightning, Priroda, 476:96-97(1958).
Jennings, R.C., Path of a Thunderbolt,New Scientist,13(no270):156,Jan18,1962
Jensen, J.C.: Ball Lightning, Physics (now J.Appl.Phys), 4:372-374(1933)
Kuhn, E.: Ein Kugelblitz auf einer Moment-Aufname?,
Naturwissenshaften, 38:518-519(1951)
Muller-Hillebrand, D.: Zur Frage des Kugelblitzes, Elektrie,17:211-214(1963)
Wolf, F.: Interessante Aufnahme eines Kugelblitz,
Naturwissenshaften, 43:415-417(1956)
Television Shows
----------------
"TLC Presents: Electric Skies" (1994), The Learning Channel
"Giants in the Earth", Arthur C.Clarke's Mysterious World,Yorkshire TV(1980)
Ball Lightning Theories
-----------------------
Arabadzhi, V.I.: The Theory of Atmospheric Electricity Phenomena, Uch.Zap.
Minsk.Gos.Univ., im A.M. Gor'kogo, Ser. Fiz.-Mat., no. 5, 1957. (Trans-
lation avail. as RJ-1314 from Associated Technical Services, Glen Ridge,NJ
Cerrillo, M.: Sombre las posibles interpretaciones electromagneticas del
fenomena de las centellas, Commision Impulsora Coordinadora. Cient.,
Mexico, Ann., 1:151-178 (1943)
Dawson,G.A., and R.C. Jones, Ball Lightning as a Radiation Bubble, Fourth
International Conference on the Universal Aspects of Atmospheric
Electricity, Tokyo, Japan, May, 1968.
Finkelstein and Rubinstein: Ball Lightning, Phys. Rev., 135:A390-A396(1964)
Kapitza, P.: The Nature of Ball Lightning, Dokl.Akad.Nauk SSSR, 101:245-248
(1955). In Russian.
Neugebauer, T.: Zu dem Problem des Kugelblitzes, Z.Physik,106:474-484(1937)
Silberg,P.A.,Ball Lightning and Plasmoids,J.Geophys.Res.,67:4941-4942(1962)
Uman, M.A.: Some Comments on Ball Lightning, J. Atmospheric Terrest. Phys.,
30:1245-1246 (1968)
Uman, M.A., and C.W. Helstrom: A Theory of Ball Lightning, J.Geophys.Res.,
71:1975-1984(1966)
Uman, M.A., and J.J. Lowke: "Decaying Lightning Channels, Bead Lightning
and Ball Lightning" 4th international conf. on the Universal Aspects of
Atmospheric Electricity, Tokyo, Japan, 1968.
--
Michel T. Talbot
bo...@freenet.carleton.ca