1. Isobars and Air Pressure
Eric Angat
Teacher

2. Isobars line of constant pressure

3. line of constant pressure
Isobars
line of constant pressure
What is the direction of the wind?
Low pressure means bad weather. The wind rotates COUNTERCLOCKWISE.
High pressure means good weather. The wind rotates CLOCKWISE.

4. Air Pressure Explained!
What happens to the density of air as we go higher up in the atmosphere?
When does air contract?
When does air expand?
What is a barometer?
What does it mean by low pressure (L)?
What does it mean by high pressure (H)?

5. Air Pressure Explained!

6. Air Pressure Explained!
1. What happens to the density of air as we go higher up in the atmosphere? 2. When does air contract? 3. When does air expand? 4. What is a barometer? 5. What does it mean by low pressure (L)? 6. What does it mean by high pressure (H)?
The density of air decreases because of lower air pressure.
Air contracts when it is cooled.
Air expands when it is heated.
Barometer is an instrument that measures air pressure.
Low pressure means bad weather and precipitation.
High pressure means good weather.

7. Isobar Contours 7. What is the average atmospheric pressure?
What are low pressures?
What are high pressures?
What is the interval between isobars?
Which states have bad weather?
What do you notice about the distances between isobars in areas of low pressure compared to the area of high pressure?

8.
Isobar Contours

9. Isobar Contours 1013 millibars
7. What is the average atmospheric pressure?
What are low pressures?
What are high pressures?
What is the interval between isobars?
Which states have bad weather?
What do you notice about the distances between isobars in areas of low pressure compared to the area of high pressure?
1013 millibars
Lower than 1013 millibars is low pressure.
Higher than 1013 millibars is high pressure.
Interval is 4 millibars
Arizona and Tennessee
Isobars in low pressure areas are closer to each other while isobars of high pressure areas are farther away from each other.

10. http://www. howmanyarethere

11. 13. How do I draw Isobars

12. Isobars are lines of constant pressures.
Isobars have intervals of 4 mb.
1024
1022
1036
1027
992
996
1033
1000
1029
1035
1004
1008

13. Isobars are lines of constant pressures.
1024
Find the lowest air pressure that has an interval of 4.
1022
1036
1027
1033
1029
1035

14. Isobars have intervals of 4 mb.
1024
Connect the isobars starting from 1024 mb.
1022
1036
1027
Not windy
1024 mb
1033
1029
1035
1028 mb
1032 mb
windy
1036 mb

15. Isobars are lines of constant pressures.

16. 13. How do I draw Isobars
Isobar lines are drawn across equal air pressures with interval of 4 millibars. When isobars are close to each other, it is windy. When isobars are farther away from each other there is light wind.

17. Predict the Weather 14. What are isobars?
15. What kind of wind is present when isobars are close together?
16. What kind of wind is present when isobars are wider apart from one another?
17. Why do we need to know the direction of the wind when predicting the weather? Think!

18. Predict the Weather

19. Predict the Weather 14. What are isobars?
15. What kind of wind is present when isobars are close together?
16. What kind of wind is present when isobars are wider apart from one another?
17. Why do we need to know the direction of the wind when predicting the weather? Think!
Isobars are lines of constant pressures.
Wind is strong.
Wind is light.
So that we can predict the direction of the front.

20. http://www. howmanyarethere

21. 18. Using the weather map,
identify the air pressure in the following states.

22. 16 20 16 12 24 H 8 L

23. KEY:
a. California __1016__________
b. Nevada _____1020______________________
c. Utah, Wyoming, Colorado ______1024______
d. North Carolina _______1012_____________
e. Indiana, Ohio, Kentucky ______1008________
f. Wisconsin _________1012________________
19. Which states are experiencing good weather?
______ Utah, Wyoming, Colorado _________
20. Which states are experiencing bad weather?
____ Indiana, Ohio, Kentucky ______