Tornadoes sometimes occur when this type of activity is present. Air-mass thunderstorms are subdivided into several types. In this text, however, only two basic types are discussed, the convective thunderstorm and the orographic thunderstorm. Convective thunderstorms may occur over land or water almost anywhere in the world, Their formation is caused by solar heating of various areas of the land or sea, which, in turn, provides heat to the air in transit. If the circula-tion is such that cool, moist, connectively unstable air is passing over the land area, heating from below causes convective currents and results in towering cumulus or thunderstorm activity.
Dissipation usually begins during the early even-ing hours.
Storms that occur over bodies of water form in the same manner, but at different hours. Sea storms usually form during the evening after the Sun has set and dissipate during the late morning. Both types of convective thunderstorms occur in Florida. The anticyclonic circulation around the Bermuda high advects moist air over the land surface of Florida in its easterly flow. Thunderstorms off the east coast of Florida at night occur when this easterly flow passes over the warm axis of the Florida current.