How does the water kept in an earthen pot (matka) become cool during summer?
An earthen pot has a large number of tiny pores on its body.
Hence, a small amount of water seeps out from these pores a nd gets evaporated from the surface.
The heat required for evaporation comes from water inside the pot
Hence, the water inside the earthen pot keeps losing heat, thus remaining cool.
Thus, water kept in an earthen pot (matka) becomes cool during summer.