Winds

-Air Pressure
-How air pressure affects human body
-Measuring air pressure
-Wind shear
-Global Wind Patterns

Air is made up mostly of molecules of nitrogen and oxygen. The molecules are zipping around at incredible speeds. Near the Earth's surface, they are traveling an average of about 1,600 feet per second or 1,090mph. The average speed increases with temperature. The molecules bump into and bounce off each other, and the impacts of those billions of bouncing molecules cause pressure.

How air pressure affects human body

How air pressure affects human body Since human beings evolved in an environment where the air pressure doesn't change rapidly, our bodies have trouble handling rapid increases or decreases in air pressure. That's why airplanes or even fast elevators can make us uncomfortable.

Air pressure inside and outside middle ear normally is equal. But, as a person goes up, the outside pressure decreases, leaving the pressure inside the middle ear higher. The air inside the ear usually moves through the Eustachian tube to the throat, equalizing the pressure. However, if a person has a cold, the Eustachian tube might be blocked, making it harder for the air to leave the middle ear and causing a sense of fullness or pain.

Despite ear discomfort, air pressure can also cause pain in sinuses and tooth abscesses.

Measuring air pressure

Evangelista Torricelli, a Galileo's assistant, invented the mercury barometer in 1643. Mercury barometers used today to measure sir pressure are little changed from Torricelli's original. A mercury barometer is a simple instrument. A tube that is closed at one end is filled with mercury and put, open end down, into a container of mercury. An inch ruler is attached next to the tube. Air pressure on the mercury in the container keeps the mercury in the tube from flowing out. The greater the air pressure, the higher the mercury will rise in the tube. Reading can be obtained and the air pressure is calculated inches of mercury.

Since a mercury barometer is bulky and inconvenient, aneroid barometers are more common than mercury barometers. An aneroid is a flexible metal bellows that has been tightly sealed after having some air removed. It might remind you of a tiny accordion. Increased outside air pressure squeezes the flexible metal; decreased pressure allows it to expand. It can be attached to a pointer or a moving pen to keep a pressure record.

Would you like to make YOUR OWN BAROMETER?

Wind shear

Wind shear refers to a quick change in wind speed or direction. Difference in wind speeds stirs up eddies that cause turbulence. Wind shear is found in jet streams 35,000 feet up, at the ground and all altitudes between.

Global Wind Patterns

Global Wind Patterns

Trade winds blow generally from northeast to southwest in the Northern Hemisphere. For hundreds of years, sailing ship captains, including Christopher Columbus, sailed far enough south to catch the steady, easterly trade winds that pushed them westward to the Caribbean. To return to Europe, they sailed northward close to the North American coast until they found the westerly winds that predominate in the temperate latitudes.

The formation of trade winds is as follows

1. Air, heated by warm water, rises over tropical oceans, forming huge thunderstorms.

2. Air flows in to replace the rising air.

3. In the Northern Hemisphere, Coriolis effect turns the southward-bound wind to its right, creating northeast winds.

4. In the Southern Hemisphere, Coriolis effect turns the northward-bound wind to its left, creating southeast winds.

5. Trade winds converge in the region of thunderstorms.

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