Answer the following Questions Briefly:

What are isotherms?

Isotherms are imaginary lines drawn on maps which join the regions having equal temperatures at a given time or on the average over a given period. Isotherms are commonly used in meteorology to show the distribution of temperature at the earth’s surface or on a chart indicating constant level or constant pressure. They are also used to show the time variation of the temperature with height in the atmosphere or with depth in soil or water.