SUMMARY
In this study, Pasquill atmospheric stability determined at daytime for January and July 2010 fixed for Baghdad city. The classification of stability was made using data of wind speed and solar radiation. These classes were compared with atmospheric stability recorded hourly in Baghdad airport station. The results show that stability class, B and C make up the highest percentages, while class A is non-existent during winter "this" can be attributed to prevailing parameter weather and their frequencies such as temperature, wind speed, and solar radiation. The stability classes were estimated to be medium to moderate. In summer, B and A-B stability classes were more predominant than others. Visibility in January month is very high and concentrated at 8500-11500 meters and has a rate of 75%, while the bad visibility range at this month is about 7.6%. In July month the rate of clear weather conditions of visibility is about 65.8%. Atmospheric elements (temperature, relative humidity wind speed, solar radiation) are compared with visibility at specified stability class to show it’s affected on visibility. If more stable conditions existed this refers to the better extent of visibility, this means unstable conditions reduce atmospheric visibility with help of atmospheric elements. Overall, the most affected class on the visibility is neutral condition and near-neutral condition, but you may determine the location if there is near to the location of emission pollutant or aerosols, consequently, the case is different.