Abstract
When the rain drop falls through the atmosphere, it always meets with air resistance, and gradually condenses or evaporates. Then the falling velocity of the water drop varies with time. The equation of the motion of the water drop is as follows where σ, is the density of the water drop.
p, the density of the air. φ, the coefficient of air resistance. I have solved the equation by means of the Bessel function and have calculated numerically.
