Question

Water is kept in other pot is cool why

Answer 1

Earthen pots are porous. Water kept inside seeps out & wets the outer surface. Dry air outside helps in evaporation of this water. The latent heat of evaporation is taken from the pot & and the water inside. Thus even warm but dry air of inland tropical areas make the water cool. Desert air coolers based on the same principle are also very popular. However, these do not work effectively in coastal areas due to high humidity in air.

Answer 2

Water looses its temperature through small pores present in the pot. Hence in an earthen pot (matka) become cool durping summer.