1. Characteristics of the atmosphere

2. ATMOSPHERE The atmosphere is a mixture of gases that surrounds Earth.
Nitrogen is the most common atmospheric gas. (78%)
Oxygen is the second most common atmospheric gas. (21%)
The remaining 1% is made up of carbon dioxide, argon, water vapor, and other gases.

3. Pressure and Temperature
Air pressure is the measure of the force with which air molecules push on a surface.
Air pressure is strongest at the Earth’s surface.
As altitude increases air pressure decreases.

4. Air Temperature Air temperature changes as altitude increases.
Temperature differences result from the way solar energy is absorbed as it move through the atmosphere. Some parts of the atmosphere are warmer because they contain a high percentage of gases that absorb solar energy. Parts that contain less of these gases are cooler.
Air Temperature

5. Layers of the Atmosphere
Troposphere
Mesosphere
Stratosphere
The lowest layer of the atmosphere, in which temperature decreases at a constant rate as altitude increases.
The layer of the atmosphere that is above the troposphere and in which temperature increases as altitude increases.
The layer of the atmosphere between the stratosphere and the thermosphere and in which temperature decreases as altitude increases.

6. The uppermost layer of the atmosphere, in which temperature increases as altitude increases.
Thermosphere

7. IONSPHERE
OZONE LAYER
The lower part of the thermosphere where atoms absorb harmful solar energy
Electrically charged gas particles are called ions.
Charged particles in the ionosphere cause auroras (northern or southern lights)
Layer found in the upper stratosphere where ozone absorbs ultraviolet radiation from the sun.
The ozone layer protects life by absorbing the harmful ultraviolet radiation.