Isopleth map

http://dwb4.unl.edu/chem/chem869v/chem869vlinks/weather.about.com/newsissues/weather/library/weekly/aa071600a.htm

This is an isopleth map that demonstrates the different ph levels of acid rain across the US. Notice the Northeastern United States have the most basic rain on the pH scale. That is where most of the industry began and this is where most of the industry in the United States still exist. There are many large cities in this area which contribute to this basic pH. This is an isopleth map because it has lines that connect two equal points. Enjoy!!!