Water is warmed by the sun and evaporates because

Water evaporates in the presence of heat`

Explanation:

Evaporation is  the most important aspect of hydrological cycle. Studies show that water evaporates because of the heat that it absorbs. The heat of the sun breaks the energy of the water molecules and transforms the water into gas or vapour.

This process of change of state from liquid to gas is known as the process of Evaporation. Water evaporates rapidly at the boiling point. The atmosphere has mostly evaporated water as its humidity.