Why do you sniff when you wish to smell something better?

Answer 1

To understand this, you need to fist understand the basic mechanism of how the sensory pathway in the nose works.

When you breathe, air enters your nostrils, reach the roof of the nose where there is a part of bone (that forms the floor of the brain) that has minute holes in it, called the cribiriform plate. It is through this part of the skull that sensory nerves associated with smell communicate with the outside.

When you sniff, which is nothing but take a deep breath, more air reaches the roof of the nose, and more signals are transmitted to the part of the brain that helps in recognizing smell.