Question

why evaporation is called surface phenomenon?

Answer 1

because if the surface area increases the more sunlight will fall on it and the evaporation will be faster. So it is called a surface phenomenun. 

Answer 2

Evaporation depends upon the surface area of the liquid. Liquid on top of the surface evaporates faster. And as surface area increases evaporation increases. Because due to more surface area more wind will strike the liquid and give the liquid molecules enough energy to break the inter molecular bonds and evaporate. Due to increase in the surface area more sunlight will fall on the liquid so that it evaporates faster. Hence evaporation is called a surface phenomenon..

I hope this will help you...