Sunnier Climes in the UK

Even in the UK, with its mid-latitude oceanic climate, solar energy is of increasing importance for maintaining energy supplies and moving towards net zero. Quantification of the solar resource therefore is critical. Measurements of sunshine duration, which are strongly correlated with insolation, indicate a continuation of a brightening trend first identified for other locations twenty years ago. Although there is likely to be some control by atmospheric pollution, decreasing cloudiness may be the main determinant. Application of Jenkinson-Collison surface synoptic indices indicates a strong synoptic control on sunshine duration but does not account for the observed trend in sunshine. This suggests that further research is warranted on circulation-related cloud attributes.