Temperature

Temperature is a physical quantity related to heat and cold.

Two bodies in contact tend to equalise their temperatures by exchange of heat to establish thermal equilibrium. Thermometers provide a measure of temperature by using phenomena such as the variation in pressure of a gas or the thermal dilatation of a body.

The S.I. unit of temperature is the Kelvin; the degree Celsius is commonly used.

Statistical physics shows that temperature is a manifestation on a macroscopic scale of the movement of atoms and molecules. It is directly related to the mean kinetic energy of the microscopic constituents of the material.

Thermodynamics. Temperature is an intensive variable. Along with pressure, its value determines the state of pure bodies.

Temperature is measured on the Kelvin scale (K symbol), equal to °C + 273°. Thus the diurnal temperature of 20°C on Earth is equal to 293K, and on the surface of the Sun 5500°C is equal to about 5770K.