Page 78 - James Rodger Fleming - Fixing the sky

War and the Weather

In America, the enthusiasm for “harvesting the storm” with gunpowder and
other explosives was just beginning. During the Civil War, some observers began
to suspect that the smoke and concussion of artillery fire generated rain. After
all, didn’t it tend to rain a day, or two . . . or three . . . following most battles? The
heavy fighting at Gettysburg on the first three days of July 1863 under fair skies
was followed by torrential downpours on July 4 that lasted all day and into the
night, resulting in roads knee-deep in mud and water that hampered the Con-
federate retreat. Skeptics hastened to point out that the connection between war
and the weather was an ancient one—and a shaky one.
In Plutarch’s “Caius Marius” (75 c.e.), “it is observed, indeed, that extraor-
dinary rains generally fall after great battles; whether it be, that some deity
chooses to wash and purify the earth with water from above, or whether the
blood and corruption, by the moist and heavy vapors they emit, thicken the air,
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which is likely to be altered by the smallest cause.” According to William Jack-
son Humphreys, Plutarch’s first option was a matter of belief, not science, while
his second option was not significant, since only about 0.01 inch of rain would
fall over a square mile if ten thousand soldiers, assuming they were nothing
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but blood and sweat, “were wholly evaporated and then all condensed back.”
Humphreys posed a plausible explanation for the apparently high correlation
between rains and battles. He noted that plans were usually made and battles
fought in good weather, so that after the battle in the temperate regions of
Europe or North America rain will often occur in accordance with the natural
three- to five-day periodicity for such events. Perhaps generals simply preferred
to fight under fair skies, with rainy days therefore tending naturally to follow.
Perhaps it would tend to rain several days after doing most anything!
In 1871 Chicago civil engineer and retired Civil War general Edward Powers
published his book War and the Weather, or, The Artificial Production of Rain,
in which he reviewed the weather following selected battles and contended that
rain followed artillery engagements—usually within several days. Powers found
a “perfect explanation” for this in the theory of oceanographer Matthew Fon-
taine Maury, who maintained that there were two great atmospheric currents,
the equatorial and the polar, flowing aloft in nearly opposite directions. Pow-
ers argued that the concussion of battle caused these higher strata to mix and
release their moisture. He envisioned stimulating rainfall on demand through
the agency of loud noises, perhaps by detonating explosive charges carried aloft
by kites or balloons. In times of drought, when the ground was bone-dry, he
envisioned tapping into the elevated rivers of air that carried abundant moisture

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