Air Currents

Air Currents
By Madison Nef
An air current is moving air, like a gust of wind. Wind is created because of uneven heating of the Earth’s surface. Since Earth is made of land and water, it absorbs the sun’s radiation unevenly as well. The wind is caused by hot and cold air interchanging places. This is caused because hot air is lighter than the cool air, and when the cold air moves in to the hot air, the wind blows. The different temperatures of air are caused by the different climates on Earth. Some places always have direct sunlight, while other places only get indirect light (causing the difference in air).
A gust front is a leading edge of cool air that rushes down from a thunderstorm. There are two reasons why air flows out of thunderstorms so quickly. The main reason is dry air in the lower atmosphere, which causes the rain falling through it to evaporating (in effect cooling the air). Being cool air sinks, it causes a downward gust of air that spreads out at the ground. The very edge of the “pool” of air is the gust front. The second reason is that the rain puts a drag on the air, which forces it downward. If the wind following the gust front is very strong, the windstorm is called a downburst.
Downbursts are created as soon as a strong wind hits the land or water and spreads out. Unlike tornados, downburst spread out immediately. Dry downbursts are generated from thunderstorms with very little precipitation while wet downbursts are generated from thunderstorms with heavy rainfall.
A derecho is a very widespread and strong windstorm that is usually found in fast moving and severe thunderstorms. Derechos can extremely damage property and are life-threatening if very strong, mainly because of the high downburst winds. To be classified as a derecho, the path of the storm must be at least 280 miles long. Widths of the storms vary usually from 50-300 miles. Derechos usually do not strike in the winter, but occur mainly in July, spreading into the early spring and summer months.
Another type of wind is a jet stream. Jet streams are a fast-flowing river of air often found in the atmosphere 12 km above the Earth’s surface. They often form at the edges of adjacent air masses with large differences in temperature- a good example being the polar region and the warmer air to the south. The streams always flow from west to east because of the rotation of the Earth- moving in a serpentine or wave-like manner at lower speeds than the wind within the flow.
While windstorms at high speeds can be extremely dangerous, wind is also very useful in the world. Not only is it the fastest growing source of electricity in the world, it is also one of the least expensive forms of renewable power. Experts actually say it can sometimes be the cheapest form of ANY kind of power. As if that isn’t great enough, generating power from wind leaves no dangerous waste behind- and its power supply is unlimited. To utilize the wind, windmills are used. The wind flows over the airfoil shaped blades causing lift, like the effect on airplane wings, causing them to turn. The blades are connected to a drive shaft which turns an electric generator, producing electricity.
Different regions have separate names for the wind. Here are some of the terms:
chinook-(westerly wind off the eastern side of the Rocky Mountains)
santa ana-(easterly towards Southern California )
scirocco-(southerly from North Africa to southern Europe)
mistral-(northwesterly from central France to Mediterranean)
marin-(southeasterly from Mediterranean to France)
bora-(northeasterly from eastern Europe to Italy)
gregale-(northeasterly from Greece)
etesian-(northwesterly from Greece)
libeccio-(southwesterly towards Italy)