Why is fog usually seen in morning?

A fog is just a cloud at the ground.Fog formation can occur in many ways.When the air is cooled to the dew point which leads to Formation of fog.and when water evaporate from the surface into the air it raise the dew pint until condensation occurs.
When the sun rises the air and ground warm up which leads to the air temperature being warmer than the dew point temperature which causes the fog droplets to evaporate.so when sun rises there is no fog.