Isobars

On a weather map an isobar is a line drawn on a map connecting points of equal barometric pressure. You will see them utilized with weather maps. This is an Isobar Map of sea level pressure in millibars. It shows that the least amount of sea level pressure is located around Ohio, and the most amount of pressure is off of the coast of Washington and Oregon and northern Texas and Oklahoma.




http://weather.unisys.com/surface/sfc_con_pres.gif