A Study of Linke Turbidity Factor over Qena / Egypt

Data on instantaneous atmospheric Linke turbidity factor TL (m) are reported for clear days at Qena / Egypt in the period from June 1992 to May 1993. TL (m) is determined using the values of irradiance of direct solar radiation (I), which are calculated from global (G) and diffuse (D) - solar radiation measurements. Monthly and seasonally va?riations of both diurnal and daily average values of TL (m) increases steadily in the direction of sunset in the months from June to December 1992 as well as Summer and Autumn seasons, while it falls generally in this direction for the months from January to March and Winter season. In April and May, TL (m) fluctuates obviously through the day hours. It is also shown that the average values of TL (m) are particularly large during Summer months compared to other months of the year. This behavior of TL (m) is discussed in view of the variations of some weather elements, which affect the content of water vapor and dust particle in the atmosphere of the study region. It seems t be of simi?lar trends to that of other locations inside and outside Egypt. The virtual variation of TL (m) is eliminated by re?ducing its value to relative optical air mass m = 2, according to Kasten formula. The resulting TL (2) is more represen?tative for the content of dust particles and water vapor in the atmosphere.