Question

How does the water kept in an earthen pot (matka) become cold during summer ?

Answer 1

An earthen pot has a large number of extremely small pores on its wall. Some of the water, continuously keeps seeping through these pores. This water evaporates continuously and absorbs its latent heat, required for vaporization from the earthen pot and the remaining water in the pot. In this way, the remaining water loses heat and gets cooled.