WHY IS RAIN FALL MEASURED IN MM? I am not sure aboout measuring rainfall in mm???

Question

Why isnt it measured in cm and other units??

Please explain?

Answer 1

Because sometimes we only experience very very small amounts of rain, thus centimetres are too large to accurately portray the amount of rainfall.

"Most rain gauges generally measure the precipitation in millimeters. The level of rainfall is sometimes reported as inches or centimeters." wikipedia

Answer 2

Rainfall is measured in mm because there's places on Earth where not much rainfall occurs (deserts, some mountains, etc.). So if you were to increase the unit of measurement by which it's measured then you would end up with and insignificant figure in the front of the number for areas where not much rainfall occurs. Also, mm is a very accurate measurement.