Isotach Map

http://www.hpc.ncep.noaa.gov/research/mcs_web_test_test_files/Page1947.htm
The map shown above is an example of an isotach map. An isotach map is a type of contour map that is used by meteorologists to illustrate different wind speeds in an area. The map above shows different winds speeds in America, and the contour lines connect areas of equal wind speeds together. The regions in green have lower wind speeds, such as the south-east, whereas the areas in yellow and red have higher wind speeds, such as the north and mid-west. These areas are more likely to receive weather changes, and isotach maps allow meteorologists to better perceive these changes.