what is the approximate speed of a rain drop before it hits the ground at ocean level?

Question

kph or mph are both acceptable

Answer 1

A falling spread-eagled human would accelerate up to about 120 mph, but at this point, aerodynamic drag would be equal to the force of gravity, so the person would stop gaining speed. This is known as the "terminal velocity" of the object.

Small objects have more drag for their weight than large objects, so their terminal velocity is lower.

A typical raindrop has a terminal velocity of about 10-20 mph.

Answer 2

In short, large raindrops (5mm diameter) will fall at about 9 m/s, smaller ones (2mm diameter) will fall at about 6.5 m/s.

There is no single formula for the terminal velocity for all sizes of raindrops. For small drops, air drag is proportional to velocity (Stokes law); for larger drops, the drag is proportional to the square of the velocity. A complete treatment also includes the viscosity of the air.

For a simple representation, see the first link below (at U. of Arizona). The second link is more detailed, it quotes some scientific papers on research in the field.

Answer 3

You need the Stokes formula for this - http://en.wikipedia.org/wiki/Drag_force#Velocity_of_falling_object

Or, if you don't want to do the math, just scroll down, there will be approximate expression for rain drops.