Question

why cooller cool better on s hot day day

Answer 1

on a hot day normally ppl sweat a lot now when that happens then if that same person is put near a cooler then the water vapour on their body cools and when it cools it takes more time to warm up and when that happens then a person feels cooler

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.