METR 104:
Our Dynamic Weather
(w/Lab)
Lab Exploration #4:
Introduction to Contour Maps
Dr. Dave Dempsey
Dept. of Geosciences
SFSU, Fall 2012

(5 points)
(Lab Section 1: Wed., Nov. 7; Lab Section 2: Friday, Nov. 9)

Objectives. By the end of this lab exploration, students should be able to:

Materials. Maps of pressure and winds based on observations recorded at 12Z October 25, 2012:

Introduction. Contour maps are a very commonly used method of showing the distribution of almost any quantity in space. Since spatial patterns of temperature, pressure, humidity, wind speed, etc. are very important for understanding and forecasting the weather, meteorologists rely heavily on contour maps to help them visualize the state and evolution of the atmosphere. You'll need to learn to interpret contour maps of weather observations, and there's no better way to do that than to learn how they're drawn.

Part I: Tutorial on Contour Maps


Using a Web browser, access the University of Wisconsin's on-line tutorial on drawing contour maps. Guided by the instructor, work through the first three lessons.

Part II: Drawing and Interpreting A Temperature Contour Map

For this activity, you'll prepare a contour analysis of a temperature map and answer several questions about it. Turn in your contour analysis and written responses to the questions at the end of the lab session.

  1. On the accompanying plot of surface temperature and wind observations for the Oklahoma area at 14Z on Thursday, Oct 25, 2012, draw and label contours of temperature (that is, isotherms) at intervals of 5°. The contours should include the 50°F contour line, but start with the lowest value justified by the observations and work up from there to the highest value justified by the observations.

  2. At places where the temperature is higher than anywhere else around it, if any, write an "H" on the map. At places where the temperature is lower than anywhere else around it, if any, write an "L". (These are maxima and minima in temperature. If a maximum or minimum is at the edge of the map, don't identify it with an "H" or "L" because the temperature could be higher or lower beyond the edge of the map.)

  3. On the map, identify (circle and label) the place(s) with the largest temperature gradient. Explain why you picked this (these) location(s).

  4. On the map, identify (circle and label) a place (if any) where you think that cold (air) advection is relatively large. Explain why you picked this location (or why you picked none).

  5. On the map, identify (circle and label) a place (if any) where you think that warm (air) advection is relatively large. Explain why you picked this location (or why you picked none).

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