The yogee/yogi sits in a comfortable posture [aasana], puts one palm on the other palm [anjale], makes own lips take the form that resembles "the bird's beak," then slowly sucks in the air from outside through this bird's beak.

The Plausible Explanation:

The water drops are present everywhere on this earth, in the form of the moisture in the air. The geography students know very well that the water molecules evaporate from oceans, then form into clouds which condense on striking against a mountain and precipitate in the form of the rainfall.

Somewhat similar must be happening during the aforesaid yogeek action [kreyaa] - the yogee must be sucking-in unwittingly the moisture from the surroundings, which must then be condensing into own mouth after which it must be precipitating in the form of the refined water drops.

The yogee must be swallowing/gulping these water drops down, thereby providing the own physical body with the required nourishment for physical survival. Of course, this mastery must be attained over a very long period of yogeek practice by the yogee!

The Usefulness:

1. The travelers lost in the remote areas with nothing to eat can probably survive by using this survival technique.
2. The military personnel, especially the commandos dropped with little or no food- stuff behind the enemy lines can survive for weeks together without having to bother for food.
3. The space-travelers can survive without food for long duration in the outer space.
4. The financially poor people who cannot afford even two square meals a day can probably overcome their hunger easily through the sufficient practice of this yogeek technique.