1. The Atmosphere Atmosphere Composition - 76% Nitrogen - 23% Oxygen
Chapter 17
Atmosphere Composition
- 76% Nitrogen
- 23% Oxygen
- Also contains:
water vapor- source of clouds and precipitation
ozone- blocks UV rays

2. Atmosphere Structure * Air pressure decreases with height
* Temperature generally decreases with
height
Temperature Layers
1) Thermosphere- hottest layer (top)
2) Mesosphere- coldest layer
3) Stratosphere- contains ozone
4) Troposphere- weather occurs (bottom)

3. Atmosphere Structure

4. Earth’s Effects on the Atmosphere
- Rotation – Earth spins on its axis
- Revolution – Earth orbits the sun
* Earth is tilted 23.5 degrees
- remember: Earth’s tilt causes seasons
Example
Summer – tilted toward the sun (more daylight)
Winter – tilted away from sun (less daylight)

5. Tilt of Earth’s Axis

6. Earth’s Tilt and the Seasons

7. Heat
- energy moving from one area to another
- Temperature- measure of moving energy
Types of Heat
1) Conduction- energy through matter
2) Convection- energy moving inside matter
3) Radiation- energy given off an object
* Heat moves from HIGH to LOW!!*

8. Types of Energy Transfer (heat)

9. Solar Radiation Effects
1) Absorbs into objects
2) Bounces off objects
3) Goes through objects
Examples
-Greenhouse Effect- gases in the air that trap
radiation
- Albedo- radiation reflected by a surface
ex.- clouds block radiation during day (cooler)
clouds trap radiation at night (hotter)
- Land heats & cools faster than water

10. Solar Radiation Effects

11. Albedo

12. Isotherms
lines on weather maps that connect points where temperature is the same
- generally run east - west & show a decrease in temperatures from tropics toward the poles