By: Shiven Patel
Basic Information on Winds
What is Wind?
Wind is the horizontal movement of air from a high air pressure to a low pressure area. There are two types of winds - Global Winds and Local Winds. All other winds are named by the direction they come from.
What Causes Wind?
Wind is caused by the differences in air pressure due to unequal heating heating of the Earth's surface.The process starts at the heating of the air, and when it is heated, it decreases and becomes less dense. Then, as the air becomes less dense, its air pressure expands. Air in a less heated area will be cooler and denser. This cool, dense air with a high pressure flows under the warm air that's less dense, causing it to rise, creating the process of wind.
What is a Local Wind?
Local winds are a type of wind that blow over a short distance. These winds are not constant and their speed and direction change. A local wind is caused by the unequal heating of Earth's surface. There are also two different types local winds - Sea Breezes and Land Breezes.
What is a Land Breeze?
A Land Breeze is a type of Local Wind. It blows from the land to the sea. At night, the land and water cool, but the land cools faster than water. Because of this, the water doesn't cool off as much and becomes warmer than the land. The warmer, less dense, less pressured air above the water rises. The cooler, more dense, more pressurized air from the land moves across the land towards the sea. This is called a Land Breeze. This process only occurs during night.
What is a Sea Breeze?
A Sea Breeze is a type of Local Wind. It blows from the sea to the land. During the day, the sun's rays heat up the land and water. Since land heats up faster than water, the air above the land is warmer than the air above the water. The cooler, more dense and less pressurized air above the sea moves towards the land. The hot, less dense air with more pressure above land moves up, higher above the land. The air moving across the sea towards the land is called a Sea Breeze. This process only occurs during the day.
What are Global Winds?
A Global Wind is a wind that travels across a large area. They are constant, always have the same speed, and don't change direction. These winds are caused by the unequal heating of Earth's surface, just like Local Winds. This unequal heating causes giant convection currents. At the equator, warm air rises and at the poles cold air sinks. Cold air has higher air pressure, so it occurs at the poles. Warm air has a lower air pressure, so it occurs at the equator. This difference in pressure causes winds to blow from the area of higher pressure (poles) to an area of lower pressure (equator). The warm air gets pushed back towards the poles, where it becomes cool and sinks. The cold air from the poles has greater air pressure , creating winds that move towards the equator, where it rises and goes back to the poles. This is the giant convection current formed by the unequal heating of Earth's surface.
What are the Types of Global Winds?
There are several types of Global Winds. They are called Doldrums, Horse Latitudes, Trade Winds, Prevailing Westerlies, Prevailing Easterlies, and Jet Streams.
Doldrums are areas of calm, weak air located at 0 degrees latitude (equator). They don't blow in any direction.
Jet Streams are a band of very strong and fast winds located in the upper atmosphere. They blow from west to east. As the name implies, airplanes use these winds the travel faster in order to save their fuel! An airplane going from west to east will gain speed, but in the opposite direction, it will lose speed.
Prevailing Westerlies are another type of Global Wind that is found between 30 degrees and 60 degrees North or South latitude. These winds blow from the west, towards the east.
Trade Winds are strong winds located in between the equator and 30 degrees North or South latitude. They blow towards 0 degrees latitude (equator) from their location. A fun fact about these are that sailors used these winds to help them move cargo across oceans to trade with other countries!