A comparative study of temperatures of direct sunlight and air temperatures in a standard screen measured at Doha International Airport - a pilot study

Abstract

An observational campaign was conducted at Doha International Airport, Arabian Gulf to find out difference between air temperature in a standard screen and direct sunlight. Hourly observations recorded during July-August 1998 and June-August 1999 formed the basis of the study. Difference between screen temperature (ST) and outside temperature (OT) in respect of all hourly data in the above period from 0600 to 1800 hrs of local time have been computed and analysed. In order to examine the difference before sunrise and after sunset, observations were also made during 1900-0500 hrs of local time from 1^st to 18^th  of July 1998. Results of the study revealed that the magnitude of the differences between OT and ST is not as high as expected. The highest difference observed was 5.1° C on 16^th  July 1999 at 0900 hr. As anticipated, the temperature of direct sunlight between 0600 hr and 1700 hr were always higher than the screen temperature. However, after 0500 pm of local time, the screen temperatures are found to be higher than outside temperature though the sunset time in these months are after 0600 pm. The mean difference between ST and DT in June, July and August respectively found to be 1.43° C, 1.53° C and 1.67° C. The highest difference observed in these months was 3.8° C, 5.1° C and 4.1° C respectively. The study has also indicated that the difference between OT and ST is generally higher during 0900-1000 hrs of local time and lower during two hours before sunrise and sunset.