17.1


 * [[image:http://www.classzone.com/books/earth_science/terc/images/spacer.gif width="10" height="10"]] ||
 * > The weather is all around us, all the time. It is an important part of our lives and one that we cannot control. Instead the weather often controls how and where we live, what we do, what we wear and what we eat. Someone who studies the weather is called a meteorologist. Weather predictions are made by forecasters who you see on television. ||
 * > The weather is all around us, all the time. It is an important part of our lives and one that we cannot control. Instead the weather often controls how and where we live, what we do, what we wear and what we eat. Someone who studies the weather is called a meteorologist. Weather predictions are made by forecasters who you see on television. ||
 * > The weather is all around us, all the time. It is an important part of our lives and one that we cannot control. Instead the weather often controls how and where we live, what we do, what we wear and what we eat. Someone who studies the weather is called a meteorologist. Weather predictions are made by forecasters who you see on television. ||


 * > **Weather is made up of different things. Click on the different types of weather above to find out more about them and how they can be measured.** ||

> > || >  ||
 * > ** Weather Definition ** Weather is the day-to-day conditions of a particular place. **For example:** It was raining today at school. Yesterday it was sunny at home.

> ||
 * > **What is Climate?** Climate is often spoken about at the same time as weather, but it is something quite different. The climate is the common, average weather conditions at a particular place over a long period of time (for example, more than 30 years). We learn about different climates around the world. Deserts have a hot and dry climate while the Antarctic has a very cold and dry climate.

Troposphere:
The layer of the atmosphere closest to the earth is the troposphere. This layer is where weather occurs. It begins at the surface of the earth and extends out to about 4-12 miles. The temperature of the troposphere decreases with height. This layer is known as the lower atmosphere.

Stratosphere:
Above the troposphere is the stratosphere, which extends to about 30-35 miles above the earth's surface. Temperature rises within the stratosphere but still remains well below freezing.

Mesosphere:
From about 35 to 50 miles above the surface of the earth lies the mesosphere, where the air is especially thin and molecules are great distances apart. Temperatures in the mesosphere reach a low of -184Â°F (-120Â°C). The stratosphere and the mesosphere are the middle atmosphere.

Thermosphere :
The thermosphere rises several hundred miles above the earth's surface, from 50 miles up to about 400 miles. Temperature increases with height and can rise to as high as 3,600Â°F (2000Â°C). Nonetheless, the air would feel cold because the hot molecules are so far apart. This layer is known as the upper atmosphere.