Question

How many drops of rain per square meter per second hit the ground in a 50 mm/hr storm?

Answer 1

If there is anymore information you want people want me to give you please let me know.. I am really unsure on how to approach this kind of question :s

Answer 2

Think about it. A 50 mm/hr rainstorm means that 50 mm of rain will fall (everywhere) in one hour. So, 50 mm falls on each square metre in one hour. Now, try to work out how much rain will fall on one square metre in one second. One second is 1/3600 th of an hour. Once you know that, you will have to make some assumptions about how much water is in one raindrop, unless you have any further information.

If you have an estimate of the volume of a raindrop (raindrops do vary in size) and you have determined the height of the water on the one square metre surface that has fallen in one second, try to determine the volume of water that has hit the surface. The total volume divided by an approximation of the volume of a raindrop should give you a reasonable estimate. If you are up to the challenge, try solving this as a Fermi problem, doing it using mental approximations only, without the aid of a calculator.

Answer 3

Okay so I am not really sure how to approach the problem as a Fermi problem :s but the size of the rain droplet is 2mm and the mass is 4.189x10^(-6)kg i don't know if that will help out or not with this kind of problem...

Answer 4

Figure out the volume falling per unit time: depth x 1 m^2/sec

Then find the volume of a single drop.

Divide drop volume into total volume falling to get number of drops per time.