12 Mapping climate data
Of course, location — simple physical geography — is only one use for geographical maps. Once we’ve done the cartography, we can add layers showing all kinds of data about the human and natural world. These maps, too, take care to create, and they have to be read even more carefully, because they add layers of complexity and potential miscommunication.
More uses of contour lines
In addition to showing elevation, contour lines can be used to show climate data — yearly rainfall, for example, or average daily high temperature in July, or the number of frost-free days in a growing season. The lines of high and low pressure on a weather map are contour lines:
We can use more detailed maps of high and low pressure to study hurricanes and big storms. This map shows the impact of the Great Blizzard of 1888; the contour lines represent lines of constant atmospheric pressure. (Low pressure means a bad storm.)
Often color is used to emphasize the regions between contour lines rather than the lines themselves, as in this map of the United States showing mean annual precipitation:
Color can make a map look prettier, but it doesn’t always enhance understanding! Most maps of precipitation use green to represent high levels of rainfall. That’s fairly intuitive — rain forests are green and deserts are brown. But the map below reverses that color scheme, using redder colors to show higher concentrations:
The lesson here is, no matter how obvious the map’s meaning seems to be, always read the key!
In the classroom: Putting it all together
When you’re using maps in teaching, they’ll be only as useful as you make them. Everything depends on context! Sometimes it’s enough to present a map with a basic reading. Other times, you may need to combine multiple maps or add data sets and other information.
In this activity from our digital textbook for North Carolina history, we combined various maps, data sets, other primary sources, and readings on both history and science to take an interdisciplinary look at the impact of Hurricane Floyd.
- Hurricane Floyd: Mapping rainfall and flooding
- Students use maps, animations, and rainfall data to measure the impact of Hurricane Floyd in September 1999. Resources on surrounding pages provide scientific background about hurricanes and flooding along with personal perspectives of survivors.
- Next: Mapping time and place