Absolute Zero
Considered to be the point at which theoretically no molecular activity exists or the temperature at which the volume of a perfect gas is zero. The value is 0° Kelvin, -273.15° Celsius or -459.67° Fahrenheit.
Temperature
The measure of molecular motion or the degree of heat of a substance. It is measured on an arbitrary scale from absolute zero, where the molecules theoretically stop moving. It is also the degree of hotness or coldness. In surface observations, it refers primarily to the free air or ambient temperature close to the surface of the earth.
Kelvin Temperature Scale
A temperature scale with the freezing point of +273°K (Kelvin) and the boiling point of +373° K. It is used primarily for scientific purposes. Also known as the Absolute Temperature Scale. Proposed in 1848 by William T. Kelvin, 1st Baron of Largs (1824-1907), Irish-born Scottish physicist and mathematician.
Celsius Temperature Scale
A temperature scale where water at sea level has a freezing point of 0°C (Celsius) and a boiling point of +100°C. More commonly used in areas that observe the metric system of measurement. Created by Anders Celsius in 1742. In 1948, the Ninth General Conference on Weights and Measures replaced “degree centigrade” with “degree Celsius.”
Fahrenheit Temperature Scale
A temperature scale where water at sea level has a freezing point of +32°F and a boiling point of +212°F. More commonly used in areas that observe the English system of measurement. Created in 1714 by Gabriel Daniel Fahrenheit (1696-1736), a German physicist, who also invented the alcohol and mercury thermometers.