Fixed Point Properties of Water (according to International Temperature Scale of 1990, ITS-90)

• triple point temperature = 0.01 C (273.16 K)
• triple pressure = 6.1173 mb
• triple point density of liquid = 0.99978 g / cm³
• triple point density of vapor = 4.885 mg / L
• boiling point = 99.975 C at 1013.25 mb
• melting point = 0 C at 1013.25 mb

Saturation Vapor Pressure over Liquid Water(T : Temperature in Kelvin)

• Goff-Gratch Equation





where




a = -7.90298	b = 5.02808	c = -1.3816 * 10-7
d = 11.344	f = 8.1328* 10-3	h = -3.49149
est = 1013.246 mb	Ts = 373.16 K

using boiling point at 373.16 K and saturation vapor pressure at boiling point at 1013.246mb (compared with ITS-90 values of boiling point at 373.15 K with saturation vapor pressure 1013.25 mb)
 

• 6th order Polynomial (Flatau et. al.,1992) (-50 to 50C)



 

a1	6.11176750
a2	0.443986062
a3	0.143053301E-01
a4	0.265027242E-03
a5	0.302246994E-05
a6	0.203886313E-07
a7	0.638780966E-10

• Bolton (1980) (0.3% within -35C to 35C)




where T_c is the temperature in degree Celcius.
 

• Modified Clausius Clayperon Equation (0.7% @ -40C to 0.006% @ 40C)





 

• Clausius Clayperon Equation (Latent Heat of Vaporization Lv is a function of T)

(0.5% within -20C to 30 C)













To = 273.16 K	eo = 6.1173 mb	Rv = 461.50 J K-1 kg-1
Lvo = 2.501 * 106 J kg-1	cpv = 1870 J K-1 kg-1	cpl = 4190 J K-1 kg-1

(or use the melting point of water at T_o = 273.15 K with e_o = 6.107  to 6.112 mb )
 

• Clausius Clayperon Equation (constant Latent Heat of Vaporization Lv)




To = 273.16 K	eo = 6.1173 mb	Rv =  461.50 J K-1 kg-1
Lvo = 2.501 * 106 J kg-1

 (or use the melting point of water at T_o = 273.15 K with e_o = 6.107 to 6.112 mb )

Saturaton Vapor Pressure Over Ice (T : Temperature in Kelvin)

• Goff-Gratch Equation




where



a = -9.09718	b = -3.56654	c = 0.876793
eo = 6.1071 mb	To = 273.16 K

(compared with ITS-90 values of triple point of 273.16 K with saturation vapor pressure of 6.11173 mb)
 

• 6th order Polynomial (Flatau et.al. ,1992) (-50C to 0C)



 

a1	6.10952665
a2	0.501948366
a3	0.186288989E-01
a4	0.403488906E-03
a5	0.539797852E-05
a6	0.420713632E-07
a7	0.147271071E-09

• Modified Clausius Clayperon Equation (0.14% within -80C to 0 C)





 

• Clausius Clayperon Equation (Latent Heat of Vaporization Lv is a function of T)














To = 273.16 K	eo = 6.1173 mb	Rv = 461.50 J K-1 kg-1
Lso = 2.834 * 106 J K-1	cpv = 1870 J K-1 kg-1	cps = 2106 J K-1 kg-1

(or use the melting point of water at T_o = 273.15 K with e_o = 6.107  to 6.112 mb )
 

• Clausius Clayperon Equation




To = 273.16 K	eo = 6.1173 mb	Rv =  461.50 J K-1 kg-1
Lso = 2.834 * 106 J kg-1

(or use the melting point of water at T_o = 273.15 K with e_o = 6.107  to 6.112 mb )

References

• Bolton, D., 1980: The computation of Equivalent Potential Temperature. Monthly Weather Review, 108, 1046-1053.
• Emanuel, K. A., 1994 : Atmospheric Convection.  New York, Oxford University Press.
• Flatau, P.J., R. L. Walko, and W. R. Cotton, 1992 : Polynomial fits to Saturation Vapor Pressure, Journal of Applied Meteorology, 31, 1507-1513.
• Rasmussen, L. A., 1978: On the Approximation of Saturation Vapor Pressure. Journal of Applied Meteorology, 17, 1564-1565.
• List, Robert J., 1966: Smithsonian Meteorological Tables.  Smithsonian Institution.