Question

how evaporation is related to humidity

Answer 1

The amount of water vapor in a given volume of air divided by the amount of air in that volume is called humidity. It depends on the temperature as higher temperature can increase the rate of evaporation and thus the amount of water vapor in the air.

Answer 2

Hello!
Here is your answer

Evaporation being a surface phenomenon has many factors affecting it.
Humidity being one Factor is inversly proportional to evaporation

Humidity increases Evaporation Decreases
Humidity Decreases Evaporation Increases