Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1920-06-13
FREAKS OF LIGHTNING
EXPLAINED BY EXPERT
Noted Astronomer Tells OF Causes
OF Phenomena Accompanying
Electrical Storms.
4 q


Please explain what causes cleo
tricity to explode In the air. and why
IT does not tear up the ground when
1t reaches the earth?"-w. u. Goshen,
Indiana"
electricity in the air, ] suppose that
you refer TO such Phenomena us the
eiee'ric spark and lightning. Those
are not explosions in the ordinary
bensc or that word. although they
often produce explosions and explo-
sire effects.
strong flash Of lightning causes
q sudden expansion Of the air imme :
dinteiy around IT, the displaced
air instantaneously rushcs back
again TO I'LL tho momcntury vacuum.
mus giving rise to waves OF sound
which constitute the phenomena OF
thunder.
The atmospheric effect is very like
'that produced By the sudden expan-
sion OF the air around the muzzle OF
cannon as the expanding gases
rush out OF the bore. The ronr Of
cannon IL analogous TO the thun-
der OF lightning discharge. But
In which the air is expanded by
lightning and by an expansion OF
gases.
The former. being curren, O,
electricity. or OF clectrons. resisted
In its passage by a nonconductiny,
or only partially conducting. medium
uhe ntmosphcre). forces It's way
r n,f,r IN" molecules Of tho ar aud
simultaneously cSphnds the air. There
may also be other cxpansiv" action
due to repulsion between the cleo
trihed air PARTICLES. In the cage
OF an explosion OF runpOwdcr the
mir Is driven bodily aside 20 make
room for N" expanding gases.
OFTEN Makes smnIi Apprnrnnce.
When "a lightning bolt str.kos the
EfOunV lts cVcCtS usually man! =
tested only by the formation OF a
mole in the earth, the existence or
tion. unless the ground is very moist.
when there may be m explosion o,
OBSERVATION-DISCLOSURES steam. making a
little excavation.
Ordinarily the only visible onec,
OF lightning upon the soil consists
OF tube called "fuiGuritc." which
may penetrate many inches or many
feet into the ground. These tube.
stance. due. OF course. To the great
heat which has suiiccd instantly 10
met IN: sand and Other substances
constituting the soil. Moist earth be
Ing good conductor Of electricity.
the discharge is rapidly conducted
away on nl! sides, and usually with
out explosive effects
But the result - often very dr.
icren, II the lightning strikes an
object resting on the surface OF the
earth. such ar house. tree, or even
az 'EpaNl'i !NplDSlEe FVcC's
are then very common. IL there /.
my moisture present which can DC
expanded Into steam by the sudden
accession OF heat.
Trunks of Trees Split.
The trunks o, trees are occasion
ally split from end TO end by tho
instantsneoua formation OF steam in
side them, or. more frequently. their
bark Is blown on. or huge limb. arc
torn OF and nung far away There
Is NJ least one record In porrcn-
DORIS "Annnlen'o Of tho complete
nnnihila,ion OF tree BY light
Ming stroke.
One o, tho most remarkable In
7tanccs Of tho effects q, the sudden
production of steam in the trunk Of n
tree by the heating effect OF high.
ming Is that OF a great oak, 81 feet
tall. In tn. forest ot Thury. France
whose leaves. within twnnty-four
hours after II was struck. turned
yellow and began TO !ai! off. al.
though tho tree bore no apparent
marks OF tho lightning tina, had
killed II. But when tho trunk Was
carefully disse ctcd II was found TIA,
been completely separated from its
neiEhbors, so that the whole trunE