Authors : S.E. Falodun and E.O. Ogolo
Abstract: The diurnal and seasonal variations of mean Global radiation have been studied by analyzing two years data measured at the ground surface in a tropical station, Akure (7.150N, 5.120E), in Nigeria. The maximum mean Global solar radiation (which occurs around 14:00 LT ) varies in the course of the year from 512 Wm 2 in the wet season (April-october) to 543 Wm 2 in the dry season (Nov-March). The low values (and large fluctuations) of the hourly mean values recorded during the wet season are attributed to the important roles that the convective clouds and water vapour play in the atmospheric radiation budget, which is very pronounced in the tropical areas of west Africa. The daily amplitude of the Global radiation is larger for the dry season (maximum in November) than it is for the wet season (maximum in July). A lag of about 2 h is also observed between the times when the maximum of the air temperature and the mean Global radiation courses occur over the area.
S.E. Falodun and E.O. Ogolo , 2007. Diurnal and Seasonal Variations of Global Solar Radiation at Akure, South-Western Nigeria. Journal of Engineering and Applied Sciences, 2: 125-128.