5 Minutes – Silent Study Time

1. 5 Minutes – Silent Study Time • Quiz #3 Atmosphere Composition and Structure • - use your notes and quiz template to prepare.

2. II. Air Pressure

3. Can you feel air pressure? When you take off or land in an aircraft, your ears may hurt or feel uncomfortable. This is because your eardrums can feel changes in air pressure as the aircraft moves quickly up and down. But what is air pressure?

4. A. Air Pressure Basics 1. Definition: weight of all the air in the atmosphere pressing down on Earth. 2. The reason air has pressure because it has mass (you can weigh it!)

5. B. Altitude & Air Pressure Since air pressure is the weight of the air overhead, what happens to air pressure as you go up in altitude?? • The air pressure drops as altitude increases (molecules spread out.) Altimeter

6. C. Air Gasses 1. Low pressure air masses are made up of water vapor. a. water vapor has a low mass 2. High pressure airs masses are made up of nitrogen & oxygen a. N & O are high mass molecules H20 vapor Nitrogen & Oxygen

7. Changing Pressure A rising barometer = increasing air pressure. This usually means: Clear Cool Dry.

8. Changing Pressure A falling barometer = decreasing air pressure. This usually means: warm, wet, cloudy Tut tut it looks like rain

9. Air is forever trying to find… • Equilibrium • Air travels from high to low pressure. • This affects wind direction and speed.

10. Low & High Comparison Table

11. E. Wrap-Up 1. Air moves from high pressure to low pressure forming winds. 2. As a result, the greater the difference between the high pressure and low pressure areas is, the higher the wind speed is.

12. 3. Barometer- instrument used to measure air pressure a. units = millibars (mb) There are two types of barometers—mercury and aneroid.

13. CBA: Awesome Atmosphere Assignment What does the atmosphere block? Describe Bill’s “atmosphere cylinder” experiment, & what were his findings? How do pilot’s determine their current altitude? Describe the difference of air pressure between Death valley & on top of a mountain. Why the difference? Why do your ear’s pop in a plane? Order the five layers of the atmosphere from highest to lowest. Why is it warmer in low cities than in the high mountains? How are Earth’s atmosphere and a greenhouse similar? Bill must run around the track _______ times to simulate the height of the troposphere. Name three topics of the atmosphere that were described in the “weather rap.”

14. F. Understanding Pressure Maps • Isobars- areas with equal air pressure Sea- level = 1013.3 mb Denver, CO = 835 mb Meridian, ID = 975 mb

15. 2. Isobar map rules: a. If # is 499 or less, place 10 in front b. if # is 500 or more, place 9 in front c. decimal is moved before last digit. Ex. 950 = 995.0 mb d. low pressure- #’s get lower toward the middle e. high pressure- #’s get higher toward the middle

16. ISOLINE ACTIVITY: • In PEN, uncode each pressure: 103=1010.3 • In PENCIL, label the highest pressure H and the lowest pressure L. 3. For theHdraw the following isobars: 1016, 1012, 1008 mb (each in a different color) 4. For the L draw the following isobars: 996, 1000, 1004 mb (each in a different color) 5. For each wind indicator- show wind movement.

18. 1016 mb H L

19. 1016 mb H L 1012 mb

20. 1016 mb H L 1012 mb 1008 mb

21. 1016 mb H L 996 mb 1012 mb 1008 mb

22. 1016 mb H L 996 mb 1012 mb 1000 mb 1008 mb

23. 1016 mb H L 996 mb 1012 mb 1000 mb 1008 mb 1004 mb

24. 1016 mb H L 996 mb 1012 mb 1000 mb 1008 mb 1004 mb

25. Isobar Mapping Questions (in comp book) Follow up questions on separate piece of paper: • Describe the wind motion in the H. • Describe the wind motion in theL. • In what area is the wind speeds the greatest? • Winds go from ___ to ____ for pressure. • What type of weather is associated with highpressure systems? • What type of weather is associated with lowpressure systems?