1. How does the Sun warm the Earth? Look at the picture on page 364. The sunlight strikes the Earth most directly at the Equator. The sun’s rays strike the Earth at the MOST slanted angle at the poles. Why is it colder at the poles than at the equator?

2. How does the Sun warm the Earth? Define Insolation – The solar (sun) energy that reaches a planet. The Earth is shaped like a sphere and that is one reason for the difference in temperature. Define equator – An imaginary line that runs around the middle of the Earth.

3. How does the Sun warm the Earth? When the sun’s rays are spread over a larger area, like at the poles, the area receives less heat energy. Areas farther north or farther south from the equator receive less energy than at the equator. Why?

4. Sunlight Striking the Earth’s Surface

5. What are the Layers of the Atmosphere? How much of the sun’s energy is absorbed by the Earth’s surface? 50% How much of the sun’s energy is reflected by the Earth’s surface? 5% Our atmosphere contains 5 layers of gases

6. What are the Layers of the Atmosphere? Define Troposphere- The Layer of gases closest to Earth’s surface. The troposphere is about 5 to 11 miles thick. Its depth is greatest at the equator and smallest at the poles. Define weather- The condition of the troposphere at a particular time and place. In what layers does our weather occur? – Troposphere

7. What are the Layers of the Atmosphere? List the layers of the atmosphere. Start with the layer closest to the Earth and travel upward. I have started for you. 5 th Exosphere 4 th Thermosphere 3 rd Mesosphere 2 nd Stratosphere 1 st Troposphere

8. What are the Layers of the Atmosphere?

9. What are the layers of the Atmosphere? Define air pressure – the force put on a given area by the weight of the air above it. At sea level the average air pressure is 14.7 pounds per square inch. You do not feel this air pressure weight because atmospheric pressure pushes in all directions and these pushes balance each other.

10. What are the layers of the Atmosphere? Air looks empty but it is a mixture of gases such as nitrogen and oxygen. Nitrogen makes up about 78% of our air. Air exerts pressure………. – A. In all directions.

12. Warm Up

13. Demonstration Will water spill out of a glass if we turn the glass upside down? Predict: yes or no? Procedure: Mr. Davies will put a note card over a glass of water then tilt the glass upside down. Results: Did the water spill out? Yes or no? – Why?

14. What are the layers of the atmosphere? Air pressure is greater at sea level and not as great at high altitudes because the air particles are closer together, or more dense at the Earth’s surface. We can’t feel the heavy amounts of air pressure because the air inside our body pushes outwards so both the inside and outside pressures balance each other out.

15. What changes air pressure? Four variables affect air pressure. They are: – Volume – Temperature – Height above Earth’s surface – Amount of water vapor

16. Volume Define Volume- – Measure of how much space an object takes up.

17. Temperature Define Temperature- – The measure of how hot or cold the air is. When air is heated the particles spread out into a larger space. Now, because there are less particles of air, the air weighs less and the air pressure decreases.

18. Height Above Earth’s Surface There are less air particles at the top of the mountain than at sea level, so the air weighs less and the air pressure is less at the top of the mountain. At sea level the air particles are squeezed closer together so the air pressure is higher at sea level. (Sea picture on notes.)

19. Height above Earth’s surface There are more particles of air at the bottom of the mountain, so there is higher pressure Define altitude- – The height above Earth’s surface.

20. Amount of Water Vapor Water Vapor weighs less than most other gases in air. Water vapor is lighter than most gases so when water is added to the air, the air becomes lighter so moist air has less air pressure than dry air. Define Humidity- – Amount of water vapor in the air.

21. Quick Check You would expect high pressure on a (dry, cold day) or (rainy, warm day). When air is cooled the air pressure (increases) or (decreases).

22. Make a Chart Work with your table partner and make a chart to help you remember what happens to the air pressure at certain weather conditions. WeatherLow pressureHigh pressure Cold Warm Wet Dry