Winnowing in Easton's Bible Dictionary

Corn was winnowed, (1.) By being thrown up by a shovel against the wind. As a rule this was done in the evening or during the night, when the west wind from the sea was blowing, which was a moderate breeze and fitted for the purpose. The north wind was too strong, and the east wind came in gusts. (2.) By the use of a fan or van, by which the chaff was blown away (Ruth 3:2; Isa. 30:24; Jer. 4:11, 12; Matt. 3:12).