The temperature during summer is high which increases the rate of evaporation. Earthen pots are made of clay that has many pores in it. The pores increase the rate of evaporation of water as the water can move via the pores through capillary action. With the increase in the rate of evaporation, the heat energy leaves the pots in the form of kinetic energy of the evaporated water. This, in turn, keeps the inside of the pot cool and the remaining water cooler. Hence, people in villages use earthen pots in summer to cool the water.
