Isopleths

An isopleths is a feature of meteorological charts, connecting points which have an equal value of some variable at a given time and spatial area. The particular variables shown on a given chart may include values such as pressure, temperature, wind speed, etc. They are used to assist in visualizing the general features of a meteorological "field” such as an isobars or isotherms. Above, the map shown features isotherm lines showing temperatures in the United States departing from the norm. These temperature changes were being used to track hummingbirds.