Recent variations of cloudiness over Russia from surface daytime observations amg

Changes of total and low cloud frac­tion and the occu­rre­nce of diff­erent cloud types over Russia were asse­ssed. The anal­ysis is based on visual obse­rvat­ions from more than 1600meteorological stat­ions. Diff­eren­ces between the 2001–2010 and 1991–2000 years were eval­uated. In general, cloud frac­tion tends to incr­ease during the last years. A major incr­ease of total cloud frac­tion and a decr­ease of the number of days without clouds are reve­aled in spring and autumn mostly due to an incr­ease of the occu­rre­nce of conv­ect­ive and non-prec­ipit­ating stra­tif­orm clouds. In contrat, the occu­rre­nce of Nimb­ostr­atus clouds tends to decr­ease. In general, the ratio between the occu­rre­nce of Cumu­loni­mbus and Nimb­ostr­atus clouds has incr­eased for the period 2001–2010 rela­tive to 1991–2000. Over part­icu­lar regions, a decr­ease of total cloud frac­tion and an incr­ease of the number of days without clouds are noted.