Why do cumulus clouds form more often during the afternoon than in the early morning?

Question

Why do cumulus clouds form more often during the afternoon than in the early morning?

Answer 1

Due to the warmth of the Sun.

Answer 2

Cumulus clouds form when there is unstable condition in the atmosphere.When there is unstable condition, convection(vertical ascent of air) takes place.The temperature of the rising air should be more than that of the surroundings for this convection to take place.This is usually possible only when the received solar radiation is more or maximum which occurs only in the afternoon.That is why cumulus clouds are developed in the afternoon more frequently