A new perspective on surface weather maps

Few students realize that a two-dimensional weather map is actually a physical representation of the three-dimensional atmospheric conditions at a specific point in time. To picture this two-dimensional image in three-dimensional form requires abstract thinking. But once that is accomplished many of the concepts, principles, and processes conveyed by a weather map become much easier to visualize and understand. A method is presented here for transforming an abstract concept (a two-dimensional weather map) into a concrete model (a three-dimensional representation of the weather map).

Conceptually, isobars on a two-dimensional surface weather map are no different than contour lines observed on a topographic map. Whereas contour lines on a topographic map represent lines of equal elevation, isobars on a surface weather map represent lines of equal atmospheric pressure at the earth's surface (standardized to sea level). To provide my students a physical image of a two-dimensional surface weather map, I have them build a three-dimensional model using isobars as contours. Building this model requires the following materials: • A surface weather map reduced (or enlarged) to fit on a 8.5” x 11” sheet of paper (the number of copies will depend on the number of isobars on the map) • A 30” x 40” sheet of 3/16” foam core board (you could also substitute corrugated cardboard or foam trays found at supermarkets in the meat and produce departments) • An Exacto knife (you could substitute scissors, particularly if using cardboard or foam trays such as you would find at the meat or bakery departments of a grocery store) • Safety goggles if using an Exacto knife • A glue stick or adhesive spray • A metal straight edge (if using foam core board)

To get started, firmly glue copies of the weather map onto the foam core board. Using the metal straight edge and the Exacto knife, carefully cut along the edges of the map. Take one of the maps and, leaving it as is, place it on a table – this serves as your base map. Next, take another map and find the lowest pressure on the map. Use the Exacto knife to cut along the isobar that circles the low pressure and remove that portion of the foam core board. Stack that map on top of your base map. On the third map, find the isobar representing the next lowest surface pressure, cut along that isobar, and remove that portion of the foam core board. Stack this map on top of the other two. You will begin to notice how they fit together in a layered pattern. Continue with this procedure until your three-dimensional model of the surface weather map is complete.

There are several analogous features between the topographic map and your weather map. For example, just as closely spaced contour lines on a topographic map indicate a large elevation gradient and steep slopes, closely spaced isobars indicate a large pressure gradient and fast wind speeds (this is easily apparent on the weather map model you have created). Also, just as enclosed contour lines indicate a relative high or low point on the topographic map, enclosed isobars indicate areas of high and low pressure, respectively. Using this analogy, the students will see how air flows outward from high pressure and inward toward low pressure.

Keeping an extra copy of the two-dimensional map with the three-dimensional model allows students to compare the two, side-by-side, so that they can visualize what the atmosphere really “looks like” in three dimensions. Plus, if the students have been trained to read weather station models, they can see how those data fit onto a surface weather map like pieces of a puzzle. Not only have I successfully used this method in my college-level, general education weather and climate course, but I have shared this project with many middle and high school teachers at various local workshops with much positive feedback.