Why does a desert cooler cool better on a hot dry day?
A desert cooler works due to evaporation .
The water falling on the sides of the desert cooler is evaporated by the hot air. Hence, the water takes up the latent heat from the air and the air becomes cool and is spread in the room with the help of the fan.
The rate of evaporation depends upon the temperature and the humidity(amount of water vapour present in air) .
Evaporation takes place faster when
- Temperature is high
- Humidity is less
During a hot and dry day , the temperature is high and the humidity is less. Both the conditions are favourable for evaporation to take place faster.
Hence, a desert cooler cools better on a hot dry day, as compared to on a humid day.