The polar front theory says that mid-latitude cyclones form on boundaries between warm and cold air.
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He joined the Massachusetts Institute of Technology ( MIT ) faculty in 1929, where he headed the development and adoption of the polar front theory of five-day weather prediction by the Weather Bureau.
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He graduated with a B . S . degree from Princeton University in 1924, then worked at the U . S . Weather Bureau, and earned a doctorate in meteorology from George Washington University ( GWU ) in 1929 . Willett won a Guggenheim Fellowship to study then burgeoning polar front theory, what became known as the Bergen School of Meteorology, in Norway.