Land Breeze Definition

A land breeze is a local nighttime and early morning wind that occurs along coasts and blows offshore (from the land out to sea). It arises at sunset when the sea surface is warmer than the adjacent land due to the land cooling off faster and having a lower heat capacity, and continues into the early morning hours until the heating of the day begins. Although commonly associated with ocean shorelines, land breezes can also be experienced near lakes and other large bodies of water. An Overnight and Early Morning Wind Like all winds, land breezes form because of a difference in air pressure and temperature. During the day, the sun will heat land surfaces, but only to a depth of a few inches. At night, water will retain more of its heat than land surfaces. (This is because it has a higher heat capacity than land.) Land breezes usually occur at night. At night, the temperature of the land cools quickly without the insolation from the sun. Heat is rapidly re-radiated back to the surrounding air. The water along the shore will then be warmer than the coastal land, creating a net movement of air from the land surfaces towards the ocean. Why? Well, the movement of the wind is a result of differences in air pressure over the land and the ocean. Warm air is less dense and rises. Cool air is more dense and sinks. As the temperature of the land surfaces cool, the warm air rises and creates a small area of high pressure near the land surface. Since winds blow from areas of high to low pressure, the net movement of air (wind) is from the shore to the sea. Steps to Land Breeze Formation Heres a step-by-step explanation of how land breezes are created. Air temperatures decrease at night.Rising air creates a thermal low at the ocean surface.Cool air collects forming a high-pressure zone above the surface of the ocean.A low-pressure zone forms above the land surface from the rapid loss of heat.A high-pressure zone forms as the cooler land cools the air immediately above the surface.Winds aloft flow from the ocean to the land.Winds at the surface flow from high to low pressure creating a land breeze. Longer Near Summer's End As the summer wears on, the temperature of the sea will slowly rise in comparison to the daily temperature fluctuations of the land, meaning that the land breeze will last longer and longer. Nighttime Thunderstorms If there are sufficient moisture and instability in the atmosphere, land breezes can lead to overnight showers and thunderstorms just offshore. While you might be tempted to take a nighttime beach walk, be sure to follow these lightning safety guidelines to reduce your risk of a lightning strike. Watch your step as well, since storms can stir up and encourage jellyfish to wash ashore! Land breezes are the opposite of sea breezes -- gentle winds that develop over the ocean and blow onshore, keeping you cool during a scorching hot day on the beach.