A temperature scale in which the kelvin is used as the unit temperature interval. Note 1: In the International System of Units (SI), the kelvin (K) is the fraction 1/273.16 of the thermodynamic temperature of the triple-point of water. Common abbreviation K temperature scale. Note 2: The temperature 0 K is called “absolute zero,” which is equivalent to −273.16°C (degrees Celsius) or −459.6°F (degrees Fahrenheit). Note 3: When citing temperatures on the Kelvin temperature scale, the symbol ° and the word “degrees” are not used. In the Kelvin scale, temperatures are simply expressed as K or kelvin, such as 293 K (kelvin), equivalent to about 20°C (degrees Celsius). Note 4: The degree Celsius is called “an interval of one kelvin,” rather than “one degree kelvin.” Note 5: The Kelvin temperature scale was formerly called “the absolute temperature scale.” Note 6: Room temperature of 20°C or 68°F is equivalent to about 293 K. A temperature of 0°C is equal to 273.16 K (kelvin). To convert Celsius degrees to Fahrenheit degrees, use the relationship F = 9C/5 + 32 and to convert Fahrenheit degrees to Celsius degrees, use the relationship C = 5(F − 32)/9. A temperature of −40°F and −40°C may be written simply as −40° because at that temperature both scale readings are the same. Note 7: Temperature is defined as the average kinetic energy of a moving molecule. Absolute zero coincides with the minimum theoretical molecular activity, i.e., minimum thermal energy of matter, which is when the kinetic energy of molecules theoretically is 0. Note 8: For high-precision measurements at extremely high and extremely low temperatures, special temperature scales are defined by international agreement. One of these agreements is the international temperature scale of 1990 (ITS-90) which became effective January 1, 1990. Published tables delineate the corrections that must be made to the Kelvin temperature scale, and also to previous international temperature scales for conformity to ITS-90. Note 9: The kelvin, a noun, is the temperature unit of measure, such as in the expression, “The temperature must be raised ten kelvin.”. The adjective is Kelvin, such as in the expression, “We will use the Kelvin temperature scale.” See also  Celsius temperature scale,  energy,  Fahrenheit temperature scale,  temperature.