RADIATION IN THE BRITISH UPLANDS

An analysis was made of recent observations of solar radiation receipt in upland areas and the longer term data of hours of bright sunshine. Estimates were made of the means and spatial variabilities of these quantities in upland regions of the U. K. It is concluded that: 1) There is a decrease in solar radiation receipt, with increasing altitude, of 2.5-3 MJ m-2 day-1 km-1. 2) The altitudinal gradient of sunshine duration is 1.3 hour day-1 km-1. This value is consistent with the observed gradient of solar radiation. 3) In cloudless conditions, solar radiation increases by approximately 15% per 1000 m; 4) Above 100 m, the land is frequently above the level of the cloud tops,at least in the summer, so that the solar radiation receipt is as much as 35% greater on the summit of Cairngorm. - from Author