Maghrabi, A.Al-Mostafa, Z.Kordi, M.Clay, R.2011-05-232011-05-232010Journal- Association of Arab Universities for Basic and Applied Sciences, 2010; 9(1):6-111815-3852http://hdl.handle.net/2440/63794Available online 14 December 2010Analysis of the performance of physically based models was done using infrared sky temperature observations taken in Tabouk City, North-West Saudi Arabia, during winter 2005. The models used here are the Brutsaert model and the Prata model. Initially, the original coefficients are used, and then, the coefficients are adjusted according to the observed models’ response to the differences between the actual atmospheric vertical structure and the average standard conditions. The produced resulting corrected estimation has reduced the RMSE and MBE values, as compared to those obtained originally. The RMSE and MBE have been reduced from 10.5 and -10 to 3.8 and -1.6, respectively, as the coefficients for the Brutsaert model were adjusted. Similarly, for the Prata model, the RMSE and MBE in the sky temperature values have been reduced from 7.7 C and -7.2 C to 2.9 C and -1.0 C, respectively.en© 2010 University of Bahrain. Production and hosting by Elsevier B.V. All rights reserved.Journal article002010549510.1016/j.jaubas.2010.12.0032-s2.0-7995542291131157Clay, R. [0000-0002-9040-9648]