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

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Presentation on theme: "Isolines An isoline is a line connecting points of equal value."— Presentation transcript:

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

3 Examples of 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!)

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

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

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

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

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

12 Visualizations of contour lines http://geology.asu.edu/~sreynolds/topo_gallery/t opo_gallery.htm

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

15 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 Making Contours worksheets Worksheets can be printed from: http://www.rcmurphy.net/Medina%202005/docu ments/Contours123.doc

17 Highlight data points.

18 Fill in gaps in data.

19 Connect the dots.

20 Go on to the next value.

21 Making a Contour Map II

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23 Drawing Contour Maps III

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