Winnowing is used to separate lighter husk particles from heavier grains by wind or blowing air. The method is based on the fact that husk is very light whereas wheat grains are comparatively heavy. The mixture is allowed to fall from a height by shaking winnowing basket continuously. The husk particles are carried away by wind to a greater distance. The wheat grains, being heavy, fall down vertically to the ground and form a heap of wheat grains.