Meteorology: Understanding the Atmosphere            Ackerman and Knox


Temperature of a volume of air represents the average kinetic energy of its molecules.

Temperature is a measure of the average kinetic energy of a substance. There are three commonly used scales for measuring the temperature of an object. Fahrenheit (named after the German instrument maker G. D. Fahrenheit) is commonly used in the United States to report temperatures near the surface. A large body of water freezes at 32 ° F and boils at 212 ° F. The Celsius (or centigrade, named after the Swedish astronomer A. Celsius) temperature scale is based on the freezing and boiling points of water--water freezes at 0 ° C and boils at 100 ° C. This temperature scale is used everyday throughout the world to report the air temperatures above the surface. The formulas to convert between Fahrenheit to Celsius are given below.

The Celsius and Fahrenheit temperature scales are not an absolute scale in that 0 ° C is not the lowest possible temperature. The Kelvin scale (named after one of Britain's foremost scientists, William Thomson, who in 1892 became Lord Kelvin) is an absolute scale because 0K is the lowest possible temperature. As temperature is a measure of the random motions of molecules and atoms, a temperature of 0K physically means that the molecules and atoms are not moving. The Kelvin scale is used in thermodynamic studies and in mathematical equations such as the ideal gas law.