What cause Florida's afternoon thunderstorm in the summer?

Answer 1

Afternoon sea breezes develop as a result of a pressure gradient force created by heating from the sun. The sun heats the land faster than the sea, creating warm, rising thermals in the morning over the Florida peninsula. This rising air results in lower surface pressure over land relative to the sea, so air flows inward from the ocean from high pressure to low pressure.

This air moves inward from both the Gulf of Mexico and the Atlantic Ocean. The seabreezes converge over the center of Florida, usually around noon-2 PM. When the air converges, it is forced upward. If there is enough moisture and instability, this rising air will "break" the capping inversion at the top of the boundary layer and continue rising all the way up to the tropopause, forming a thunderstorm.

The storms will then move either east or west depending on the prevailing wind direction. They usually only have a lifetime of ~30 minutes because there are no upper level winds to support their updrafts. The outflow boundaries created by the seabreeze storms' cold downbursts will often converge and create additional lift and new thunderstorms.

Once the sun sets, the storms usually disappear, although they can occasionally continue to be fueled by warm sea temperatures if they move offshore, especially over the warm Gulf Stream.

Answer 2

The ground throughout the day is being heated by the sun and massive evaporation takes place. When enough water vapor accumulates in the upper atmosphere, the vapor molecules collide and join getting bigger and eventually when heavy enough they fall in the form of rain drops.