Isobar map of the United States

http://trueseminole88.blogspot.com/2011/04/isobars.html

     This is an isobar map of the United States. Isobar maps show the isobars, which are lines of equal atmospheric pressure drawn on a meteorological map. Isobar maps are most commonly used when vacationers want to take a ski trip, it is good to see what kind of elevation you will be at.