Question

Why does a dessert cooler colds faster on a hot dry day?

Answer 1

On a hot and dry day temperature increase and humidity decrease both the factors increase the rate of evaporation and creates cooling effect. Pump pour water on mats which get evaporated by fansand takes the heat from hot air and air becomes cool.

Answer 2

The particles of liquid in desert cooler absorb energy from the surrounding to regain the energy lost during evaporation. In summer this is fast. Hence desert cooler cool better in a hot dry day.