1. Isolines
An isoline is a line connecting points of equal value.

2. Examples of isolines: (The weather channel loves isolines!) Isotherms:
points of equal temperature
Isobar:
points of equal barometric (air) pressure
Contour:
points of equal altitude
Concentration of chemicals
Anything else you can get a value for.
(The weather channel loves isolines!)

6. Rules for Drawing Isolines:
1. Isolines connect points of equal value. 5 5
10
10
10
10
15
15

7. 2. Isolines are gentle, curving lines- no sharp corners.5 5
10
10
10
10
15
15

8. 3. Isolines are always closed curves even though the map might only show part of it.

9. 4. Isolines NEVER cross- this would mean that one point has two different values. Ex: one spot has two temperatures?
60 °
50 °
40 °
30 ° X
20° Z Y

10. 5. Isolines usually are parallel. (They have a parallel trend.)

11. Practice Drawing Isolines: 10 unit interval

12. Practice Drawing Isolines: 10 unit interval

14. Gradient
Gradient shows how quickly the value changes from one point to another.

15. A gentle (low) gradient changes slowly and the lines are far apart.
A steep (high) gradient changes quickly and the isolines are close together.
A gentle (low) gradient changes slowly and the lines are far apart.
Steep area
Gentle area

16. Gradient
List three situations in which it would be useful to calculate gradient.

17. Gradient Example:
On a topographic map, the elevation at your house is 480 m. A hill, 4 km away, has a height of 980 m. What is the gradient from your house to the top of the hill?
980 m m
4 km
Gradient = 125 m/km

18. Gradient Example:
 It is 7 degrees Celsius in Ithaca, and 25 degrees Celsius in Miami. Miami is 2600km away from Ithaca. What is the temperature gradient from Ithaca to Miami?

19. Gradient Example:
 Low pressure system is centered over Syracuse with a barometric pressure of 1011 mb. The barometric pressure in Norwich, 36 miles away, is 1019 mb. What is the pressure gradient?

20. Gradient Example:
 A ball rolls down a 1.5 meter plank in 2.7 seconds. The top of the plank is .7 m above the ground. What is the gradient of the plank?