Determination of Sky Temperature

The sky temperature TH (equivalent temperature of the uncovered sky for sS = 1) is given by Swinbank 1963 as:

Ts= 0.0552-Тд5 (99)

TS sky temperature in K

TA ambient temperature in K

or according to an even more simplified assumption by Whiller 1967:

Ts=TA-6K (100)

A more extensive, but more accurate method (using also relative air

humidity HR as parameter) is given by Abid 1987:

Ts – 7^(5.7723 +0.9555 +(0.6017)7)-10“4 T^imHR 00665 (101)

A comparison of the different models for the calculation of sky temperature TS is given in Fig. 7.23 as a function of ambient temperature TA. In general, further calculations were using the model from Abid 1987 at HR=40%.