Wind is an important part of weather and it can tell us a lot about what is happening in the weather around us.
Wind is invisible but we can hear it and see it.
Wind happens when air moves around.
Even though air is invisible, we can hear it when it moves through the trees and we can feel it.
The reason that we feel it is because it is made up of different gases such as oxygen and nitrogen and it has many molecules.
The molecules are what move through the air.
Wind happens when the pressures of the Earth change.
We know from different lessons that there are high air pressures and low air pressures.
When there is a high air pressure, we will feel the wind move more.
The wind moves through areas with a higher air pressure than other days.
The air pressure is mostly caused by the changes of the temperature.
When the air is cooler, it makes there be a higher air pressure and when it is warmer, the air pressure is lower.
Not only do the air pressures affect the wind, but when the Earth rotates, it also affects the wind. This is called the Coriolis Effect.
Wind can be measured! Meteorologists are able to tell what direction the wind is moving and how fast the wind is going. In order to test wind direction, flags and windsocks and weathervanes move in the direction that the air is going.
In order to test wind speed, meteorologists can use a tool that is called an anemometer and it tells how fast the wind is going.
There are other types of wind patterns that happen all over the world.
When the Earth spins, wind pressure and temperature can change.
These winds are called Polar Westerlies, Prevailing Easterlies, and Trade Winds.
A Polar Westerly happens when the wind is strong by the South Pole and the North Pole. The wind blows from the poles and goes in opposite directions.
With the Prevailing Easterlies, the winds blow in the middle of the Earth. These winds blow east to west toward the poles.
The Trade Winds happen when wind blows close to the equator from the South or the North.
When we have winds that blow close to us, they are called local winds.
Local winds blow from the ocean and these winds help to heat up the ocean faster.
In the nighttime, these winds cool things down and they cause the land to have a strong breeze.