Question

how does the water kept in an earthen pot (matka) become coid during summer

Answer 1

The water kept in an earthen pot (matka) becomes cool during summer because of the evaporation of water through the fine holes in the earthen pot which makes it cool.

Answer 2

THIS IS THE REASON -(PURE SCIENCE)
the matka has holes from which it will seep out and evaporate. however to evaporate it needs heat right ? so it absorbs heat from the matka and evaporates... so the matka remains cool as its heat was taken away . this way water remains cool.