1. Drawing Isobars:
Isobars are lines drawn to connect identical values shown on maps…

2. Drawing Isobars:
In meteorology, isobars are used to connect points of equal atmospheric pressure…

3. Drawing Isobars:
This information will graphically depict weather phenomena that can be used in forecasting…

4. Drawing Isobars:
Let’s begin by using the blank Weather Forecasting Review Worksheet…

5. Drawing Isobars:
Using a pencil, you will lightly draw lines connecting identical values of sea level pressure.

6. Drawing Isobars:
Isobar lines do not cross each other.

7. Drawing Isobars:
Isobars are usually drawn for every four millibars using 1000 millibars as your starting point.

8. Drawing Isobars:
Therefore, these lines should have values of 1000, 1004, 1008, 1012, 106,etc., or 996, 992, 988, 984, etc.,

9. Drawing Isobars:
Begin drawing from 1024 millibars station pressure over Salt Lake City…

10. Drawing Isobars:
Draw a line to the next 1024 value located to the NE as shown..

11. Drawing Isobars:
Without lifting your pencil from the paper, continue drawing a line connecting the 1024 values located in the SE and SW

12. Drawing Isobars:
Repeat the procedure for the next isobar value of 1020

13. Drawing Isobars:
Repeat the procedure for the next isobar value of 1016

14. Drawing Isobars:
Repeat the procedure for the next isobar value of 1016

15. Drawing Isobars:
Repeat the procedure for the next isobar value of 1012

16. Drawing Isobars:
Repeat the procedure for the next isobar value of 1008

17. Drawing Isobars:
Repeat the procedure for the next isobar value of 1008

18. Drawing Isobars:
Your finished drawing should look something like this:

19. Drawing Isobars:
These isobars can be used to identify ‘High’ and ‘Low’ pressure systems… A B
Which of these systems is a ‘High’ pressure system?

20. Drawing Isobars:
A is a high pressure system A

21. Drawing Isobars:
Draw a large ‘H’ in the center of the high pressure system as shown H

22. Drawing Isobars:
In a high pressure system, winds revolve around it in a clockwise direction… H

23. High Pressure Systems
In high pressure systems, wind direction is created by the sinking of cooler, drier air…

24. Drawing Isobars:
B refers to a ‘low’ pressure system B H L

25. Drawing Isobars:
In a low pressure system, winds revolve around it in a counter-clockwise direction… B H L

26. Drawing Isobars:
In most cases, these air pressure systems move in a west to east direction… H L

27. Low Pressure Systems
In low pressure systems, wind direction is created by the rising of warm, moist air…

28. Drawing Isobars:
If we ignore the numbers, this is how the map might look after 24 hours… L H

29. Drawing Isobars:
This information will graphically depict weather phenomena that can be used in forecasting…