The National tribune. [volume] (Washington, D.C.) 1877-1917, 1890-04-03
Ito be coaiinucd3
THE WEATHER.
Some Facts About Thundcrstorms.
BY LIEUT.. J. P FINLEY. U. g. SIGNAL SERVICE

BY LIEUT.. j. p. FINLEY, u. &. SIGNAL SERVICE.
fCoTrespondence invited. suggestions desired
aud information cheerfully furnished. Every ef-
fort employed to make this Bureau of practical
To the readers OF ,fnE NATIONAL Tribune. All
communications should nc Hidres-ed- Heather.
TnK NATIONAL TRIBUNE Office. Washington. ID. C.l
We havo shown In previous articles that the
atmosphere ordinarily contains large guam.
tity Of electricity.
Since dry air is q non conductor the electri-
fed PARTICLES IN clear weather are in a measure.
insulated. and tho electricity cannot acquire
euch intensity. But when the vapor OF the
air Is prcciptatcd aud a cloud Is formed. the
electricity which WAS previously confined 10
the separate particles Of the air now fnis a
conducting medium more less perfect, and
it spreads Itself over the surface OF tho cloud.
thereby acquiring considerable intensity. IL
is generally Admitted that the same quantity
OF electricity which exists in the cloud existed
in the air before the formation OF the cloud
aud that the cloud performs no other Office
than that OF conductor.
A cloud thus electrified must necessarily have
positive electricity. since in clear weather the
electricity of the atmosphere Is always positive.
Such cloud when IL approaches near another
cloud having less electricity, none ut all. acts
lay Induction upon the latter, accomplishing its
natura electricity, attracting the negative
e"irclririty aud reueiling the positive The pos
bc drawn or by tho near approach of another
cloud. This operation explains the frequent
alterations % positive and negative electricity
observed during thunder shower.
1--WE clouds having opposite oleetricities at
tract each other, aud when tho clouds come
sufficiently near the two clectricties rush to-
ward each other with great violence. This
phenomenon is called lightning, and is accom-
pam ed 10y an explosive noise called thunder.
When the electricity of one part of cloud
Ia discharged. the electricity of distant part
of the cloud is hut slightly changed. because
clouds arc very imperfect conductors of cleo
triCity.
single discharge docs not establish com-
plcte electrical equilibrium, but there is
change in tho distribution of tho electricities
upon the surrounding clouds. aud there must
be n succession OF discharges before the cleo
triciiy is entirely neutTaliIed. This explains
the succession of flashes Of lightning and pcals
Of thunder.
cloud charged with electricity exerts an
inductive influence upon the earth's surface
Immediately beneath ii. decomposing its nat
ural electrieities. repeling electricity of the
same kind aud attracting the opposite kind.
Accordingly there will sometimes be dis
churge of electricity from the cloud TO the
earth This charge Is usually received by the
most elevated objects. such rs mountains hills,
trees, spires. high buildings. etc. Trees are
particularly exposed 10 strokes OF lightning on
account of their elevation, as we'll rs of tho
moisture which they contain. anI which rem
dcrs them partial conductors of-the electric
fluid.
Thunder storms generally occur during and
after The hottest part OF the day, viz, about ,
p. IN. Under peculiar conditions Of heat aud
moisture electrical storms may occur in the
moruing, when their severity is proverbal
Thunder In the morning
The sailors take warning.
Thunder storms are local in character. and
therefore Indicate that abnormal conditions
give rise TO them. They almost invariably do.
velop in the southeast quadrant of lO,U. where
exist the highest gradients ia temperature aud
moisture. This quadrant is the local storm
quadrant OF low where form all classes of
such disturbances. such as tornadoes, hail
storms. whirlwiuds and thunder storms.
IL L. a