Abdullahi M., Nasir M. A. and Singh S. K.
Solar radiation which is the electromagnetic energy from the Sun(both total and in various wavelengths) varies at different time scales from seconds to decades or centuries— as a consequence of solar activity. The energy received from the Sun is one of the natural driving forces of the Earth’s atmosphere and since this energy is not constant because of the changing of day and night times, it has been argued that there must be some non-zero climate responsible for it. This response must be fully specified in order to improve our understanding of the climate system and the impact of anthropogenic activities on it. However, despite all the efforts, if and how subtle variations of solar radiation affect climate and weather still remains an unsolved puzzle. One key element that is very often taken as evidence of a response is the similarity of periodicities between several solar activity indices and different meteorological parameters. The coefficients ‘a’ and ‘b’ were calculated from equations (6) and (7) to 0.33 and 0.46 respectively. Equation (8) was used in calculating the clearness index for Yola (9.140N of latitude) which appeared to show the clearness of the sky of Yola from February to July and October to December