1. Title: Air Pressure Notes
EQ: How does air pressure determine the weather?

2. Everyday is a holiday!
National Knee Day!

3. 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!)
*Let’s prove it!!!!!

4. B. Altitude & Air Pressure
The air pressure drops as altitude increases (molecules spread out.)
Altimeter

5. 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

6. D. Low & High Comparison Table
Atmospheric condition
Pressure
Temp.
Humidity
Gasses
Result
Low
Cooler
Greater
Water vapor
(low mass)
Cloudy & precipitation, unsettled
High
Warmer
Lesser
Oxygen & nitrogen (high mass)
Clear & stable
D. Low & High Comparison Table

7. E. How air moves
1. Air moves from high pressure to low pressure forming winds. 2. Wind speed is determined by how close the difference in air pressure is.

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

11. Let’s Practice Label the 3 yellow numbers: Fastest wind Moderate wind
slowest wind
Let’s Practice

13. Title: Isobar Map Challenge
Map #1 drawing instructions: 1. Draw in the following isobars using a smooth curved line. Please use PENCIL , 990, 994, 996, 998, 1000, 102, 1004, 1006, mb 2. Locate the area of highest pressure on the map. Using a blue colored pencil, write in the letter “H” to represent the center of high pressure. Using the same colored pencil, draw arrows around the “H” clockwise to show how winds travel around high pressure systems. 3. Locate the area of lowest pressure on the map. Using a red colored pencil, write in the letter “L” to represent the center of low pressure. Using the same colored pencil, draw arrows around the “L” counter clockwise to show how winds travel around low pressure systems. 4. Using an orange colored pencil, shade in the area of the highest wind speed. 5. Using a purple colored pencil, shade in the area of the lowest wind speed. Map #1 Analysis Questions: 1. Look at the area that you shaded orange. How can you tell these are where the highest wind speeds are located? 2. Look at the area that you shaded purple. How can you tell these are where the lowest wind speeds are located? 3. Which state(s) are most likely receiving precipitation currently? 4. What geographical direction is the high pressure center most likely traveling?

14. Map #2 drawing instructions: 1. Find the lowest millibar on the map. 2
Map #2 drawing instructions: 1. Find the lowest millibar on the map. 2. Draw a 992 isobar curved line with pencil. 3. Continue drawing isobar lines in increments of 4 mb up to the 1028 mb. 4. Locate the area of highest pressure on the map. Using a blue colored pencil, write in the letter “H” to represent the center of high pressure. Using the same colored pencil, draw arrows around the “H” clockwise to show how winds travel around high pressure systems. 5. Locate the area of lowest pressure on the map. Using a red colored pencil, write in the letter “L” to represent the center of low pressure. Using the same colored pencil, draw arrows around the “L” counter clockwise to show how winds travel around low pressure systems. 6. Using an orange colored pencil, shade in the area of the highest wind speed. 7. Using a purple colored pencil, shade in the area of the lowest wind speed. Map #2 Analysis Questions: 1. In part of the United States is the high pressure center located? 2. In what part of the United States is the lower pressure center located? 3. On which side of the low pressure center would the winds be the strongest? Which state(s) are most likely receiving precipitation currently? 4. What geographical direction is the high pressure center most likely traveling? 5. In the next two days, what should the people of New York expect to happen to the local air pressure? 6. Describe the weather that is approaching the New York area.

15. 2. Isobar map rules: a. If # is 499 or less, place 10 in front b
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 = mb d. low pressure- #’s get lower toward the middle e. high pressure- #’s get higher toward the middle

16. ISOLINE ACTIVITY: (Get 6 different colors)
In PEN, uncode each pressure: 103=
In PENCIL, label the highest pressure H and the lowest pressure L.
3. For the H draw the following isobars: 1016, 1012, 1008 mb (each in a different color)
4. For the L draw the following isobars: , 1000, 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. Follow up questions on separate piece of paper:
Describe the wind motion in the H.
Describe the wind motion in the L.
In what area is the wind speeds the greatest?
Winds go from ___ to ____ for pressure.
What type of weather is associated with high pressure systems?
What type of weather is associated with low pressure systems?

26. #8 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.”