On the Relation between Solar Incidence and Cloud Coverage

[摘要] A computing formula of the intensity of insolation which reaches the horizontal area on the earth's surface is presented, where the shielding effect of cloud, the absorbing and scattering effect of water vapour and air molecules, and the variation of the sun's zenith distance are considered. In order to calculate the contribution of cloud coverage, two layer model of cloud is used, and 0.44 and 0.36 are adopted as mean albedos of the lower and the upper cloud layers, respectively. For the determination of the transmission coefficient due to water vapour and air molecules, Kimball's graph is used. As the result, it is proved that the introduction of this effect improves the result considerably.

[学科分类] 大气科学