1. Isolines and Topographic Maps

2. DO NOW What is an isoline?
An isoline is a line connecting points of equal value.
What are isolines that connect equal points of temperature called?
Isotherms
What are isolines that connect points of equal pressure called?
Isobars

3. Topographic Maps Contour Line –
- line on a map that connects points of EQUAL elevation.
- show elevation and shape of the land

4. Topographic Maps
Two dimensional model of the Earth’s surface (represents 3-D world)
Topographic maps are also known as contour maps.
Show elevation above sea level using contour lines.

5. Topographic Maps Contour Interval –
difference in elevation between each line. MUST be equal spacing.
Contour interval =
20 feet
580
560
540
520

9. “Real World”
Contour Map

10. Rules for Contours
1. Contours bend upstream (uphill) when crossing a stream.

12. 399
179
239

13. Rules for Contours
2. The maximum possible elevation for a hill is “1” less than what the next contour “should” be.
The highest possible elevation of the hill is just below the value of  the next line that is not shown 90 80 70 60 50

14. Closely Spaced Contours
Steeper Slope (Gradient) – contour lines are closer together.

16. Wide Spaced Contours
Gradual/Gentle Slope (Gradient) – contour lines are farther apart.

18. A B

19. Depressions
Contour lines which show a depression, crater, or sinkhole on a map.
Shown by dashed lines on the inside of a contour line

20. 100
100 50

21. Rules for Contours
The lowest possible elevation for a depression is “1” more than what the next contour “should” be.
The lowest possible elevation of a depression is just above the value of  the next line that is not shown 90 90 51 80 70 60 50

22. Let’s make a map!!
Contour map 1

23. Highlight data points.

24. Fill in gaps in data.

25. Connect the dots.

26. Go on to the next value.

27. Another map!!
Contour map 2

29. Isotherms
Lines on a map that connect points of equal temperature

30. What is an Air Mass?
Air masses are large bodies of air which have similar temperature and moisture characteristics.
Air masses form when air stays over a region (called the source region) for several days.
Air masses that form over water will be moist.
Air masses that form over land will be dry.

31. A = Arctic P = Polar T = tropic
c - continental = dry m - maritime= moist
A = Arctic
P = Polar
T = tropic

32. Isobars
Lines on a map that connect points of equal pressure

33. Pressure- Measured with a barometer
Pressure is the weight of air pushing down.
Describes the air systems that cause weather.
HIGH PRESSURES:
Cooler
Less Moisture
Clear Skies H
Good Weather 
LOW PRESSURES:
Warmer
More Moisture
Precipitation Likely
Bad Weather  L