Variability of nephological conditions in 1971–2010 based on measurements made at Bydgoszcz-Airport weather station

Abstract

Abstract This paper contains a description of nephological conditions in the Bydgoszcz area based on data sourced from the Bydgoszcz-Airport weather station for 1971–2010. In the analysed forty-year period from 1971 to 2010 the average annual total cloud cover in Bydgoszcz – measured on a scale of 0–8 – was 5.5; for the warm season (April – September) it was 5.1, and for the cold season (October – March) 5.8. This corresponds to, respectively, 69, 64 and 72% coverage of the sky by cloud. Cloud cover was largest from November to February (6.1–5.8) and smallest in August (4.7). In 1971–2010, the average mean cloud cover value (scale 0–8) decreased from 5.6 in 1971–1990 to 5.4 in the multi-annual period 1991–2010 (by 0.05 per 10 years).