Isopleth Map

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


The above illustration is an example of an isopleth map which shows a line on a Cartesian nomogram where all the points represent a certain value of a variable.  An example of this could be an isobar on an isopleth and each of these lines have points along them of equal value. Above is an example as it would apply to the United States.