1. Characteristics of the Atmosphere

2. Composition of the Atmosphere
The atmosphere is primarily composed of Nitrogen (78%) and Oxygen (21%)
Other components are present which include
Argon (1%), "greenhouse" gases (0.01%)
Ozone (O.01%) Carbon Dioxide ( %)

4. The first layer closest to the earth is the troposphere.
This layer contains about 90% of the total mass of the atmosphere.
This is where all plants and animals live and breathe.
Climate and weather also occur in this layer.

5. The next layer is the stratosphere.
It extends to about 30 miles above the earth.
Ozone in this layer stops many of the sun's harmful ultraviolet rays from reaching the earth.

7. Approximately 90% of the ozone in the atmosphere resides in the stratosphere.
Ozone absorbs the bulk of harmful ultraviolet radiation.
Increased penetration of ultraviolet radiation to the planet's surface would damage plant life and have harmful environmental consequences.
Large amounts of solar ultraviolet radiation would result in a dramatic increase in cancers.

8. The third layer is the mesosphere
The third layer is the mesosphere. The temperature can drop to -173 degrees Fahrenheit.
This is where we see "falling stars," meteors that fall to the earth and burn up in the atmosphere.

9. The thermosphere layer has many temperature changes
The thermosphere layer has many temperature changes. Energy from the sun is absorbed and bounced back. The top of this layer can get to 441 degrees Fahrenheit.