Wind

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What is Wind?

Whoosh! You know that wind is moving air. But what causes the air to move? It’s the uneven heating of the earth’s atmosphere.

As the sun warms the earth’s surface, the atmosphere warms too. Some parts of the earth receive direct rays from the sun all year and are always warm. Other places receive indirect rays, so the climate is colder. Warm air, which weighs less than cool air, rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow.

Wind Makes Weather

from http://chainreaction.asu.edu/weather/digin/windmake.htm

Wind can be many things. A gentle breeze on a warm spring day is welcome and soothing. But the powerful swirling winds of a tornado or hurricane hold some of Nature's most powerful destructive force. Breeze or gale, wind is really nothing more than hot and cold air in motion.

The world's winds are part of a global system of air circulation that moves light hot air toward the poles and the heavy cold air toward the equator. When dense cold air meets hot air, the cold air is sucked under the rising hot air. A low pressure front is created. Wind blows wherever there is a difference in air temperature and pressure.

Low-pressure zones are characterized as wet and stormy weather. These zones come with gray skies and high winds.

Wind by Scholastic

Q: Why do we have wind, and how does it get so powerful?
A: There are several reasons usually working together that make the wind flow. One is differential heating of the earth by the sun. One spot is warmer so air rises and cold air, which is heavier hurries in to fill the void. The same differential heating on a grand scale results in high pressure and low pressure centers on the earth. The air rushing from the highs into the lows are the winds we talk about when we see the fronts on weather maps. Friction (buildings and other things on earth) deflect the air, sometimes squeezing, sometimes opening, increasing or decreasing the wind. And finally, the spinning Earth adds some curvature to the wind like a pitcher throwing a curveball. (Al Peterlin)

Q: Why it is always so windy during the month of March in Virginia?
A: March is a windy month in many parts of the United States and, in fact, the Northern Hemisphere. There are several reasons, but all relate to the strength of the high and low pressure systems that move through our atmosphere. In March, the cold air over the arctic had ample time to pool or collect. At the same time, the sun, which had been heating the far South more strongly than the North, is already starting to move northward (actually the earth's rotation and tilt changes) bringing stronger bubbles of warm moist ocean air. When the strong, cold high from the arctic rushes toward the deep, warm low from the Tropics, the winds gust very strongly, trying to reduce the vast temperature differences between the two air masses. If two weak air masses meet, we experience light winds. When two strong air masses meet, we feel strong winds. (Al Peterlin)

What is Wind?
Wind is moving air. We can use the energy in wind to do
work. Early Egyptians used the wind to sail ships on the Nile
River. People still use wind to move them in sail boats.
In Holland, people used windmills to grind wheat. The
Pilgrims used windmills to grind corn, to pump water, and
to run sawmills. Today, we use wind to make electricity.

THE SUN MAKES THE WIND BLOW
The energy in wind comes from the sun. When the sun shines, it heats the earth.
The air over the land gets hotter than the air over the water. The hot air rises and
cooler air rushes in to take its place. The moving air is wind.

WIND ENERGY IS RENEWABLE

As long as the sun shines, there will be winds on the earth. We will never run out
of wind energy. It is a renewable energy source. It is also free, since no one can
own the sun or the air.


WE CAN CATCH THE WIND
Some places have more wind than others. Areas near the water
usually have a lot of wind. Flat land and mountain passes are good
places to catch the wind, too.
Today, we use big windmills to catch the wind. Sometimes, there are hundreds of
windmills in one place. This is called a wind farm. Some are as tall as 20-story
buildings!

WIND CAN MAKE ELECTRICITY
When the wind blows, it pushes against the blades of the windmills. The blades spin
around. They turn a generator to make electricity. The windmills don’t run all the
time, though. Sometimes the wind doesn’t blow at all. Sometimes the wind blows
too hard. Most windmills only run about two-thirds of the time.
Today, wind energy makes only a
little of the electricity we use––
enough to power a city the size of
Chicago, Illinois. Most of the big
wind farms are in California. There
are plans for many more all over
the country.

WIND IS CLEAN ENERGY
Wind is a clean energy source.
Windmills don’t burn fuel, so they
don’t pollute the air. Older
windmills were sometimes very
noisy, but the new ones are not.
One windmill doesn’t make
much electricity. Most wind farms
have many, many windmills. Wind
farms take up a lot of land; most of
the land they are on can still be
farmed or used to graze animals.
Wind is a safe, clean energy source
for making electricity.