Graphic created by Stacey Schlessler Osborne of The Laurel Outlook.
During World War II, Japan released 9,300 balloon bombs that were intended to be carried to the United States by a high altitude wind known today as the "jet stream". Less than 400 of the bombs are known to have made the 6,000-mile journey. At least 35 of these bombs are known to have landed in Montana. At the start of the balloon-bomb program, which ran from November 1944 to April 1945, Americans were still unaware of Jet Streams. However Japan realized that these winds could transport the bomb-carrying balloons to the United States within days. Although the position and speed of the jet stream is variable, in the winter it often streaks across the Pacific from Japan to the United States. When inflated with hydrogen, each 33-ft. wide balloon could carry up to 794 lbs. of ballast and bombs. As they floated upward to a height of 4-8 miles they were taken into the jet stream and carried at speeds of up to 200 miles per hour toward the U.S.A. Little was known about the jet stream during WWII, but today meteorologists recognize the significance of these high altitude, high speed winds. Here are some jet stream facts.
1. There are other jet streams besides the one that carried balloon bombs across the Pacific. That one, the same one that often blows over Montana, is called the sub-polar jet stream.History of the balloon bomb effort . . .
As a result of the Japanese attack on Pearl Harbor (December 7, 1941), the United States sent airplanes to drop bombs on Tokyo in April of 1942. The bombing mission, known as the "Doolittle Raid", was dramatized in the recent hit movie "Pearl Harbor." In response to the raid, Japan was compelled to strike American soil. The balloon bomb program was an attempt to accomplish this. The specific goal of balloon bomb effort, which ran from November 1944 to April 1945, was to start forest fires that would destroy property and divert manpower from the war effort.
Montana, The Magazine of Western
History . . .
Term: jet stream
|*More information about the balloon bombs (includes photos)|
|What causes jet streams?|
|A book about the balloon bombs|
|*Check out maps showing the current location of jet streams|
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Earth Science Teacher at Helena High School