Scientists use line diagrams to make charts and graphs about solar radiation. Shaffer and Cerveny know that line diagrams have certain flaws. Line diagrams are difficult to interpret.
Line diagrams don't provide good pictures of the information they are supposed to be describing. A line diagram of weather patterns on Earth gives the same amount of space to the polar regions as it does to the equator. It makes Earth seem like a cube. All six sides of a cube are the same size.
Earth is definitely not a cube. It is more like a squashed sphere. The area of polar regions is smaller than the area of regions around the equator.
Geographers call Earth's equatorial region the mid-latitudes. The region covers the area of the world between 30 degrees North and 30 degrees South.
The latitude of 30 degrees North is less than 100 miles south of Arizona. It runs through parts of Mexico and the United States. The latitude of 30 degrees South cuts across the South American countries of Chile, Argentina, and Brazil.
Even correct measurements charted on a line diagram will always give more importance to polar conditions than to the climate at the equator. In reality, the mid-latitudes have more area than the polar regions. But on a line diagram, all the regions have the same area.
"Line diagrams may emphasize what's happening at the poles over the equator and mid-latitudes," Shaffer explains.
He and Cerveny used a computer and astrophysical information to measure incoming solar radiation. They ran a simulation of global weather patterns for the past 150,000 years.
After finishing their measurements, they gave the information to another graduate student. That student used a computer to model the new information onto a sphere. The result (see the image below) is a series of globes that show how Earth's weather has changed in the past.
Shaffer explains the main reason he and Cerveny created a new model was to correct flaws in the line diagrams.
"The second reason was to create a teaching tool," he says.—Lindsey Michaels