Corn was winnowed,
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.
By the use of a fan or van, by which the chaff was blown away (Ruth 3:2; Isaiah 30:24; Jeremiah 4:11,12; Matthew 3:12).
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Winnow'". "Easton's Bible Dictionary".