What is Winnowing? 

Winnowing is the process of separation of the heavier components from the lighter components of a mixture by wind or by blowing air.

It is generally used by farmers to separate the lighter impurities such as husk particles from the heavier grains .

Farmers use this method for separating the grains from husk and hay. When a farmer threshes wheat crops in his fields, he gets a mixture of wheat grains and husk.
Winnowing is done by using a winnowing basket.

Winnowing  method is based on the fact that husk is very light whereas wheat grains are comparatively heavy.

Process of Winnowing 

The process of winnowing is described below.

• The mixture of wheat grains and husk is taken in a winnowing basket. The farmer stands at a higher platform from the ground and allows the mixture of wheat grains and husk to fall down from a height by shaking his winnowing basket continuously . 
• The wheat grains, being heavy, fall down vertically to the ground and form a heap of wheat grains . 
• The husk particles, being lighter, are carried away by wind to a greater distance. So, the husk forms a separate heap at a small distance away from the heap of wheat grains .
• In this way, husk gets separated from wheat grains. 

The method of winnowing is used to separate husk from various types of grains like wheat, rice etc.

Limitation of Winnowing in Separation 

We cannot separate small stone particles from wheat by the process of Winnowing.

This is because stone particles are quite heavy which cannot be carried away by wind to a greater distance than wheat grains.