Where Weather Happens

& other important stuff about the atmosphere

What is the atmosphere, anyway?

•The atmosphere of the Earth is a mixture of gases surrounding the planet and held in place by gravity.

• It gives us the air that we breathe; • It plays a major role in the water cycle; • It allows the warmth of the sun to reach us; and• It protects us from harmful ultraviolet rays.

What does the atmosphere do, exactly?

The atmosphere has five broad layers with distinct characteristics.

Between each layer is a boundary that separates one layer from another.

The troposphere is the layer closest to Earth’s surface.

Tropos is a Greek word meaning “to turn or change.” The troposphere is where warm and cold air mix constantly.

It varies in thickness from about 5.5 miles at the poles to about 10 miles at the equator.

This is the area where weather occurs.

About 90% of the entire mass of the atmosphere exists here.

The tropopause is not a layer; it is the boundary between the troposphere and the next layer, the stratosphere.

The stratosphere is the next layer.

Stratus is a Latin word meaning “stretched out” or “layered.” The stratosphere contains the ozone layer, which is what protects Earth from the intense heat of the Sun. Temperature rises at the top of this layer. Water vapor in the troposphere does not reach the stratosphere, so it is relatively calm and stable here. Military planes fly and weather balloons collect information at this level .

The stratopause is not a layer; it is the boundary between the stratosphere and the next layer, the mesosphere.

The mesosphere is the atmospheric layer above the stratosphere.

Its name comes from the Greek mesos, meaning “middle.”

In the mesosphere, the temperature becomes colder as altitude increases. The coldest atmospheric temperatures occur here—as low as -140°F!

The air here is very thin, but it is thick enough to slow down meteorites which burn up as they hurtle into it, making trails of fire.

The mesopause is not a layer; it is the boundary between the mesosphere and the next layer, the thermosphere.

The thermosphere is next.

Thermosphere comes from the Greek word, therme, meaning heat.

Temperatures can exceed 3,100°F in this layer of very thin air.

Auroras occur in this atmospheric layer.

Examples of Auroras

The exosphere (from the Greek,

exo, meaning outer or outside) is the

uppermost layer of the atmosphere. It

marks the transition into

outer space. It is the only layer in

which atmospheric gases can escape

into space.

Make a drawing of the layers of the atmosphere.

Title it “Layers of the Atmosphere,” and draw something that is characteristic of each level, based on your notes.