CONTOUR MAPS…

Exercise – contour today’s (or yesterday’s) temperatures across the conterminous USA
LINK to raw data downloaded from a wonderful website... datastreme project of Meteorological Society.
LINK to map work sheet .. note, this exercise is for January 2010 .

PART ONE. CLASSIFY data into categories.

Note: MAP KEY in the space left and below the map. The categories are the ten degree intervals that cover the data.

First... look at the map. "Let the data look at you."

Find the lowest temperature: _____

Next, find the highest temperature: ____

Note how the intervals are listed in the key.

Take a deep breath. This is not a race. You're mastering a skill:

0- 9; 10-20; 20 – 29 degrees, etc. for the entire range

Assign a graduated color scheme: cold are purple and blue; hot are pink and red.

THEN: Classify the data points

Circle every value of the attribute temperature (note the use of language in a pedantic, role-modeling sense) on this map. When you’ve got all the values circled, then color the inside of the circle, DON'T color bands of color. Take a deep breath. Look for patterns of color.

PART TWO: Draw contour LINES in BLACK. Note… contour lines are NOT contour intervals. Contour LINES, also called contours, are hypothetical lines with the same value all along them. In contrast, contour INTERVALS have a range of values. This distinction is the key to understanding contour maps.

Draw a BLACK LINE that represents 40 degrees. It will go through all the “40s” and it will have all values warmer than 40 on one side and all values lower than 40 the other side. For example, it might have 43 to the south of it and 39 to the north of it. Draw a black (contour) line for every 10 degree line. Don’t skip values… 20, 30, 40, 50, 60, 70. It’s Okay to have “islands” It’s not Okay for lines to touch or cross. LABEL the contour lines, remember, the contour lines are black lines.

PART THREE: COLOR THE BANDS.

Use the colors of your key. Color the bands between the contour lines.

You may need to finish this at home. What I want you to understand is how contour maps are made and what they communicate. Contours represent variation in continuous data. We’ll discuss topographic contour maps, meaning contoured elevation data. We’ll discuss how shorelines, when they are created, are Nature’s contour lines.

CONGRATULATIONS… you have constructed a contour map!!