1. Topic: Characteristics of the Atmosphere PSSA: 3.5.7.C / S8.D.2.1

2. Objective: TLW describe the composition of the atmosphere. TLW describe the composition of the atmosphere. TLW explain how atmospheric pressure, temperature, and composition are interrelated. TLW explain how atmospheric pressure, temperature, and composition are interrelated.

3. MI #1: What is the Atmosphere? The atmosphere is a mixture of gases that surrounds the Earth and provides oxygen to living things and protection from the sun’s dangerous rays. The atmosphere is a mixture of gases that surrounds the Earth and provides oxygen to living things and protection from the sun’s dangerous rays.

4. MI #2: Atmosphere Composition Nitrogen (N) makes up 78% of the Earth’s atmosphere. Nitrogen (N) makes up 78% of the Earth’s atmosphere. Oxygen (O) makes up 21% of the Earth’s atmosphere. Oxygen (O) makes up 21% of the Earth’s atmosphere. The remaining 1% of Earth’s atmosphere is made of carbon dioxide (CO 2 ), argon (Ar), water vapor and other gases. The remaining 1% of Earth’s atmosphere is made of carbon dioxide (CO 2 ), argon (Ar), water vapor and other gases.

5. MI #3: Atmospheric Pressure Atmospheric (or air) pressure is a measure of the force with which air molecules push on a surface. Atmospheric (or air) pressure is a measure of the force with which air molecules push on a surface. As altitude increases, atmospheric pressure decreases. As altitude increases, atmospheric pressure decreases.

6. MI #4: Atmospheric Composition and Temperature Air temperature changes as altitude increases, but whether it goes up or down depends on what gases are found in the air. Air temperature changes as altitude increases, but whether it goes up or down depends on what gases are found in the air. Some gases absorb solar energy readily, so the temperature actually increases with elevation. Some gases absorb solar energy readily, so the temperature actually increases with elevation.

7. So What…? Real Life Application Understanding the interrelationship between atmospheric pressure, temperature, and composition is fundamental in understanding weather patterns. Understanding the interrelationship between atmospheric pressure, temperature, and composition is fundamental in understanding weather patterns.