الفهرس 
acknowledgmentOnly 14 pages are availabe for public view
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Abstract
Farticulate matter (aerosol) can be distinguished on
the bases of its size and also with respect to its chemical composition. These properties have great effect on the light scattering, visibility and climate.
In the present thesis, the technique used for determination the aerosol size distribution is the measurement of the extinction coefficient in a alant path at different wavelengths predetermined by eigenanalysis technique. easurements are inverted to obtain the aerosol size distribution.
The practical part in this thesis can be divided into two main sections:
First section: We determined the information content for each measurement at certain wavelenth, and determined the required measurements number. We found;
(1) At least, four measurements on the visible range of light and infrared range are needed to determine the aerosol size distribution for radius range from 0.01 to 1μm.
(2) Five measurements are needed to know the distribution of larger particle radii, with extension of measurement further in infrared range. It is found that the fifth measurement contribute by less than 1% of the information content. Therefore, four measurements is sufficient to retrieve 99% of the information content.
Second section: We measured the optical depth at Alexandria site for the first time, the measurements were inverted to calculate the aerosol size distribution. The result of the.