Two qualitative methods of estimating the time trend of the atmospheric air humidity case of sarh, southern part of chad period from 1971 to 2004

This study concerns the time trend of the atmospheric air relative humidity over the locality of Sarh in the southern part of Chad for the period from 1971 to 2004, almost a climatic period which was divided into seven sub periods of 5 years each. Sub period monthly and yearly means have been calculated and corresponding values compared. This comparison did not reveal significant difference between the considered values; moreover the yearly trends of the sub period monthly means were slightly the same and the time trend of the yearly means indicates that the atmospheric air relative humidity was increasing with a yearly speed of 0.2%, what is relatively not significant to produce an important impact in the on-going climatic change. More attention should be paid on the environmental impacts as this could lead to the presence of more dangerous acids in the atmosphere.