Urban-suburban/rural differences over Greater Cairo, Egypt

Abstract

"Air temperature, vapour pressure and relative humidity differences at fixed hours in urban, suburban andrural districts of Cairo area, Egypt, have been investigated using data for the 1995-2000 period. It has beenfound that, on the basis of the vapour pressure differences, the urban atmosphere is drier throughout the yearexcept for the months of December, January, May and September. In the afternoon, the atmosphere in theurban area is more humid throughout the year if compared to the suburban area and during the months fromOctober to January in addition to May if compared to the rural area. On the basis of relative humidity, theurban atmosphere is always drier than its surroundings throughout the year, except in the afternoon when theurban-rural differences fluctuated between positive and negative. The urban atmosphere is always warmerthan its surroundings throughout the year, except in November when there is a cool island. Relationshipsbetween heat island intensity and both vapour pressure and relative humidity differences reveal that localeffects can be significant."