Why does a desert cooler cool better on a hot dry day?

Q.:- Why does a desert cooler cool better on a hot dry day?

 

Answer:-

The cooling in a desert cooler is caused by the evaporation of water. A desert cooler cools better on a hot and dry day because the higher temperature on a hot day increases the rate of evaporation of water and the dryness of air (low humidity of air) also increases the rate of evaporation of water. And due to increased rate of evaporation of water, a desert cooler cools better on a hot and dry day.