1. Preview Section 1 Characteristics of the Atmosphere The Atmosphere
Concept Mapping

2. The Composition of the Atmosphere
Section 1 Characteristics of the Atmosphere
The Composition of the Atmosphere
The atmosphere is made up mostly of nitrogen gas.
Oxygen makes up a little more than 20% of the atmosphere.
Water in the form of a gas called water vapor along with tiny particles such as dirt, salt from the oceans, and ash from volcanoes make up part of the remaining atmosphere.

3. Atmospheric Pressure and Temperature
The atmosphere is held around the Earth by gravity. Gravity pulls gas molecules in the atmosphere toward the Earth’s surface, causing air pressure, which is the measure of the force with which air molecules push on a surface.
The closer you are to sea level, the stronger the force or pressure is on you. The further you travel up from sea level, the less the force is up on you and the lower the pressure.

4. Atmospheric Pressure and Temperature
Section 1 Characteristics of the Atmosphere
Atmospheric Pressure and Temperature
As altitude increases, air pressure decreases.

5. Atmospheric Pressure and Temperature
Section 1 Characteristics of the Atmosphere
Atmospheric Pressure and Temperature
Remember: Temperature is the average energy of particles in motion. High temperature means that particles are moving very fast.
Air temperature changes as altitude increases. Depending on the amount of gases that absorb solar energy, the temperature can increase or decrease in the layers of the atmosphere. When a gas absorbs energy from the sun, the air temperature goes up.
What does that tell you about the motion of the particles?

6. Facts to remember!
The atmosphere is made up of a mixture of atoms & molecules.
Air or gases are made up of matter- they have mass and take up space.
Density is the concentration of particles in a given space.
Nitrogen is the most abundant gas in the atmosphere
Earth’s atmosphere makes conditions on Earth suitable for living things.
What is the atmosphere? Name at least two gases the atmosphere is composed of.