Without the atmosphere that envelopes the Earth, we would not have weather. Indeed, we would almost certainly not exist. The atmosphere contains oxygen that is necessary for life. It also contains water vapor, which is a crucial component of weather.

Earth's atmosphere is a protective layer that also happens to be surprisingly thin. The atmosphere is made up of distinct layers. The existence of the first atmospheric layer was discovered in 1899. Research since then has identified five distinct layers that exist between the ground and outer space. All five atmospheric layers have an effect on weather and climate, but 99% of our weather occurs in the first layer, the troposphere.

The troposhere begins at ground level and extends from 5 to 10 miles high. It is lowest at the poles and highest at the equator. As you rise through the troposphere, the air temperature falls about 4 degrees Fahrenheit for every 1,000 feet of altitude. The temperature stops decreasing at the boundary to the next atmospheric level. The boundary is called the tropopause. Temperatures at the tropopause can be as low as -70 degrees Fahrenheit.

The next atmospheric layer, the stratosphere, begins at the tropopause and reaches to about 30 miles above ground level. Air temperatures in the stratosphere increase to about 40 degrees Fahrenheit. The ozone layer lies about 15 miles above the Earth's surface, which puts it inside the stratosphere.

The mesosphere is the next atmospheric level above the stratosphere. Temperatures fall again in the mesosphere, dropping to as low as -130 degrees Fahrenheit. The mesosphere extends to about 50 miles above ground level.

Above the mesosphere lies the thermosphere (sometimes called the ionosphere). Temperatures in the thermosphere skyrocket to as high as 2,700 degrees Fahrenheit. The thermosphere provides much of our protection from space debris. Meteors, satellites, and any other objects falling from space rarely survive the high temperatures of the thermosphere.

The highest atmospheric level is known as the exosphere. The exosphere contains several different kinds of gases. However, gravity is so weak at this level that molecules can escape into space, so the quantities are very small.

To sum up, most weather occurs in the troposphere, but the entire system of atmospheric layers--troposphere, stratosphere, mesosphere, thermosphere and exosphere--functions together to make life possible on earth.