Weather Station

What Is Atmosphere?

by Rebecca Jahn

Atmosphere is the huge blanket of gas that circles the entire Earth. Without it, life as we know it could not exist.

This blanket of gas starts at ground level and stretches 600 miles into the sky. However, most of this life-supporting shell is squashed down into a layer only six miles thick. The top of Mount Everest barely peeks above the edge of this layer.

The remaining 594 miles cannot support life. However, these layers do protect us from the dangers of the sun's radiation. They also protect us from drifting rocks, big hunks of metal, and other bits and pieces of space junk that collide with our planet from time to time.

The atmosphere is made of four different layers. Layer number one is called the troposphere. People, plants, animals, and insects live in the troposphere. It is the layer where all weather occurs.

Scientists who study weather are called meteorologists. They refer to the troposphere at "The Weather Zone." The troposphere begins at ground level and extends six miles up into the sky where it meets with the second layer.

Layer number two is called the stratosphere. The stratosphere begins at the six-mile point and reaches nearly 31 miles into the sky.

An important layer of atmosphere containing ozone is located inside the stratosphere. Ozone is a special form of oxygen, and the ozone layer is very important to all life on Earth. Ozone blocks large amounts of solar ultraviolet radiation from entering the troposphere. Too much solar radiation can harm living things, including people.

The third major layer is the mesosphere. The mesosphere begins 32 miles above the Earth's surface. Temperatures are warmest at the lowest level of the mesosphere and become colder at its highest level.

The thermosphere is the fourth layer and begins 50 miles above the Earth. Temperatures in the thermosphere become hotter and hotter when moving farther away from ground level. How can this be?

Together, the troposphere, stratosphere, mesosphere, and thermosphere act as a giant safety blanket. They keep the temperature on the Earth's surface from dipping to extreme icy cold that would freeze everything solid, or from soaring to blazing heat that would burn up all life.