62 Clouds, Wind, and Storms-Mid

Clouds, Wind, and Storms Written by Kira Freed

Introduction Somewhere on Earth, almost every kind of weather is happening right now. Did you ever wonder? what causes all these kinds of weather Around Earth is a layer of air called the atmosphere. The atmosphere is made of different kinds of air—warm, cold, dry, and wet. When different kinds of air move and mix with each other, it causes wind, clouds, precipitation, and storms.

Weather happens in the part of the atmosphere closest to Earth's surface. The Sun's energy hits the ground and turns to heat. Then the air above the ground heats up. Some air becomes warmer than other air. When warm and cool air mix, the result is weather. Some parts of Earth get more energy than others. The air closer to the equator gets warmer than the air at the poles. Also, dark areas absorb more heat than light areas. Finally, different places get more sunlight than others during different seasons.

Wind Wind is moving air. We can't see it, but we can feel it. And we can see how it moves plants, flags, and other things. Air moves because warm air. is lighter than cold air Air near the ground gets warmed up by the ground's heat. The warm air gets lighter, so it rises. Then colder, heavier air takes its place near the ground. The air that was warm starts to cool off higher in the atmosphere. Then as the cold air close to the ground becomes warmer, it rises. Now other cold air moves in to take its place. The cycle of heating and cooling of air makes wind.

Think about Chicago, which is on Lake Michigan. When the Sun shines, the air over land heats up more than the air over water. As warm air over the city rises, cooler air over the lake moves toward the land to take the place of the rising warm air. This causes a breeze from the lake to the land. Why is wind strong sometimes and just a light breeze at other times? Wind gets stronger as the difference in temperature between warm air and cool air becomes greater.

Changes in weather happen when air of different temperatures meets. The line where the warm and cold air meet is called a front. Fronts are where weather changes often start. Measuring the Wind We measure the wind with an anemometer. Why do people measure the wind? Here are some of the reasons. Wind speeds help scientists predict the weather. Pilots cannot take off or land if the wind is strong. Ship captains need safe winds to enter harbors. Machines called wind turbines change wind into electricity. In some places, the wind is too calm to use wind turbines.