The sun is the earth's primary source of energy. For the air to be heated the sun's rays must first heat the surface of the earth. They are then reflected from it, heating the air from the surface upward. When the sun's rays hit land, heat is concentrated in its upper surface, because the density of rocks and soil at the earth's surface prevents the rays from penetrating deeply. When the sun's rays strike water, they penetrate a greater distance, even hundreds of feet. The ground therefore heats more rapidly than water, but loses its heat more rapidly as well.
No part of Florida is more than 80 miles from a large water body. The surface water temperature of both the Atlantic Ocean and Gulf of Mexico rises to about 84 degrees F in the summer and falls to approximately 70 degrees F in the winter. This temperature range is considerably less than that of the state's land surface. The closer one lives to the sea, the stronger the influence of the water's temperature on that of the air. Average maximum atmospheric temperatures are higher in the interior than along the coast and minimum temperatures are lower, since the ground both gains and loses heat rapidly. There are substantial differences in temperatures between places on the ocean and those a few miles away: for example, between Miami Beach and Miami, 8 miles away. Temperatures over 90 degrees F are very rare on Miami Beach but quite common in Miami.
