Solution:The method used to separate the chaff from the grain by wind or blowing air is winnowing.
After the crop is reaped, the grains need to be separated from stalks, and then the undesired material, like chaff, needs to be removed from the grains. The chaff is removed from the grains by wind or blowing, and this process is called winnowing. The farmer takes the mixture into a winnowing basket and drops this mixture from a height on the ground. The heavier particles fall on the ground, and the lighter particles that are chaff are blown away by the wind and make a separate heap away from the grains. This way, the chaff is separated from the grains.