Question

Why does evaporation causes cooling?

Answer 1

In the process of evaporation the particles take energy from the surroundings in the form  of latent heat to break down the force of attraction between the particles. This makes the surrounding are cooler. That is why evaporation cause cooling.

Answer 2

Since the kinetic energy of a molecule is proportional to its temperature, evaporation proceeds more quickly at higher temperatures. As the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid decreases