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

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!)

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

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

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

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

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

Practice Drawing Isolines: 10 unit interval 95 91 85 81 80 76 75 75 76 74 79 80 82 92 84 79 77 77 76 75 77 76 75 77 79 82 89 75 68 65 66 67 63 64 65 71 75 78 81 75 72 65 58 56 49 55 61 63 66 72 75 75 79 77 77 66 51 49 47 58 63 65 67 69 67 80 77 73 61 55 47 44 55 57 59 65 64 66 81 80 78 76 62 61 59 58 57 58 59 62 65 82 83 80 78 77 72 67 63 62 60 58 62 64

Practice Drawing Isolines: 10 unit interval 95 91 85 81 80 76 75 75 76 74 79 80 82 92 84 79 77 77 76 75 77 76 75 77 79 82 89 75 68 65 66 67 63 64 65 71 75 78 81 75 72 65 58 56 49 55 61 63 66 72 75 75 79 77 77 66 51 49 47 58 63 65 67 69 67 80 77 73 61 55 47 44 55 57 59 65 64 66 81 80 78 76 62 61 59 58 57 58 59 62 65 82 83 80 78 77 72 67 63 62 60 58 62 64

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

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

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

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 - 480 m 4 km Gradient = 125 m/km

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?

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?

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?