Abstract :
The monthly mean values of global, G, and ultraviolet, UV, solar radiation incident on a horizontal surface at Cairo
urban area during the two different periods (1969–1973) and (1993–1997) are presented, analyzed and compared. The
effect of urbanization processes on the solar radiation components is investigated and discussed. It was found that the
total radiation of the two components, G and UV received at the urban area of Cairo during the period (1969–1973)
highly exceeds the radiation received during the period (1993–1997) for all months of the year. The mean relative
reduction of G and UV reached 17.4% and 27.4% respectively. A significant correlation between G and UV radiation
has been established and the recommended correlation equation has been stated to estimate the values of UV radiation
that are difficult to measure at any site in the zone of Lower Egypt. Also, a comparative study of the two
radiation components, G and UV, at urban (Cairo) and rural (Bahtim) areas during the period (1993–1997) revealed
that the urban area always has values of G and UV radiation distinctly lower than that found in rural area for all
months of the year. Urban–rural mean reduction of G and UV reached 7.0% and 17.9% respectively. The ratio of the
ultraviolet to global radiation (UV/G) are calculated and compared with other sites in the Arabian Peninsula. The effect
of atmospheric dust on the measured solar radiation components is also investigated and discussed.
2004 Published by Elsevier Ltd.
