Thunderstorm
Usually there are more clouds in the afternoon than in early morning.  This is because the ground has warmed up enough by the afternoon for winds (updrafts) to blow upward from the ground. When the air has gone high enough, the water vapor in it condenses into a cloud.  The height where this happens depends on the temperature and humidity of the air.  Sometimes the air can rise up as high as 5,000 to 10,000 feet (1,524 to 3,048 m) before a small cumulus cloud can condense from the invisible water vapor.