The sun functions as a heat source to emit warming radiation. It serves as the initial or primary temperature source. The heat must react with the atmosphere, which contains a layer of light and heavy air molecules that surround the Earth. Water must be present, and it is the varying temperatures between the solar heat and the water, in combination with the atmosphere, that start a wind cycle or sea breeze.
The conditions for the beginning cycle of a sea breeze requires a very warm or hot inland temperature. If the coastal area has numerous streets, paved areas, parking lots and building structure, the land surface area will be hotter and more heat-absorbing than a heavily vegetated area or area occupied by numerous lakes or streams. There must be a significant difference in temperature between the land and ocean's surface for a breeze cycle to begin.
The warm air occupying the land's surface heats up and begins to rise because it weighs less than cooler air. The higher the temperature, the faster the air rises. As the warm air rises, cooler offshore air rushes in to take its place, similar to filling a vacuum or being sucked in as if if affected by a pump. Equatorial coastlines, due to their higher land surface temperatures, receive stronger pumping actions. The air displacement actually creates a breeze. If the topography of the land is relatively flat, the breeze can be quite strong and travel inland for up to 25 miles.
Cool air that rushes in to displace warm rising air allows the higher air in the atmosphere to drop drown and replace the previous location of the cooler air. This creates a pressure difference, which causes the rising air to loop back out to sea at a higher elevation. The loop-back air cools, drops and joins the cycling of the cool offshore air. This creates a circular loop of current that continues to move, and only slows or stops when the land's surface air cools and fails to rise.