21-2 Temperature Scales(温标) Three temperature scales are defined Kelvin scale, Celsius scale. and Fahrenheit scale 1.Kelvin scales(7) The definition: The triple point(三相点) of water was set to be(in 1954) 7=273.16K It is one of the seven base units of sI Units Although there is no apparent limit to how high the temperature of a system can be there is a limit to how low it can be. T>0K21-2 Temperature Scales （温标） 1. Kelvin scales (T) • The definition: The triple point (三相点) of water was set to be (in 1954): • It is one of the seven base units of SI Units. • Although there is no apparent limit to how high the temperature of a system can be, there is a limit to how low it can be. T > 0 K Ttr = 273.16 K Three temperature scales are defined: Kelvin scale , Celsius scale, and Fahrenheit scale