winnow

To subject (granular material, especially food grain) to a current of air separating heavier and lighter components, as grain from chaff.

[W]ind began to winnow the river delta's dried sediments.

To separate, sift, analyse, or test by separating items having different values.

They winnowed the field to twelve.

They winnowed the winners from the losers.

To blow upon or toss about by blowing; to set in motion as with a fan or wings.

The light snow lay on the narrow and winding path before them, pure as if just fresh winnowed by the wind.

Gulls average much larger than terns, with stouter build; the feet are larger and more ambulatorial, the wings are shorter and not so thin; the birds winnow the air in a steady course unlike the buoyant dashing flight of their relatives.

To move about with a flapping motion, as of wings; to flutter.

That which winnows or which is used in winnowing; a contrivance for fanning or winnowing grain.

The act of winnowing