Results and Discussion

Climatic conditions:

The data of the climatic conditions were recorded continuously at the nearest meteorological station to the exposure site by the aid of the" Egyptian Meteorological Association". The mean values of twenty-four hours readings of temperature of the surroundings, relative humidity, incident solar energy and total sun hours were recorded as shown in table (I):

Table (1) : Monthly data of climatic conditions in

Alexandria and Helwan cities (Year:2002/2003)

Alex. : Alexandria Helw. : Helwan Temp: temperature

UV : Ultraviolet radiation J/Sq m: Joule/square meter

Monthly total incident sun hours and ultraviolet radiation:

The monthly values of the total incident sun hours falling on the earth surface which were recorded at the nearest meteorological station to Helwan and Alexandria cities, are shown in table (I). The data showed considerable variations as follows:

A maximum was observed in July and a minimum in December (Alexandria) while a maximum was observed, in August and a minimum in January (Helwan). The monthly data of climatic conditions in Alexandria and Helwan cities, are shown in table (1) where a cyclic seasonal variation of the UV Radiation J/Sq m was observed, in which a maximum value was shown in July and a minimum in December at Alexandria city while a maximum was observed in July and a minimum in January at Helwan city.