Robert Twardosz
Articles
Relationships between cloudiness, precipitation and air temperature
Geographia Polonica (2004) vol. 77, iss. 1, pp. 9-17 | 
Full text
Abstract
The work described in this paper aimed at determining the relationship between air temperature, cloudiness and precipitation, based on the Cracow meteorological records. Meteorological data from the period 1901-2000 were used. The research was based on mean monthly temperature totals; the number of days with maximum temperatures above 10°C and above 25°C; annual and daily precipitation as well as the cloud cover and cloud type in three climatic observation terms. The mean yearly air temperature was found to show steady growth, induced by both natural and anthropogenic factors. Climatic warming in Cracow probably has resulted in the more frequent appearance of convective clouds, as well as intense showers, thunderstorms and hailstorms. On the other hand, the frequency of Stratus clouds and fog has been diminished which probably contributed to a reduction in the number of days with light precipitation. No overall trend has been detected in the long-term series for total annual precipitation, as periods of high and low precipitation balanced each other.
Keywords: cloudiness, precipitation, air temperature, Cracow, Poland
[d.matuszko@uj.edu.pl], Institute of Geography and Spatial Management, Jagiellonian University Grodzka 64, 31-044 Kraków, Poland
[r.twardosz@uj.edu.pl], Department of Climatology, Institute of Geography of the Jagellonian University ul. Grodzka 64, 31-044 Kraków, Poland
[k.piotrowicz@iphils.uj.edu.pl], Institute of Geography and Spatial Management, Jagiellonian University Grodzka 64, 31-044 Kraków, Poland
Geographia Polonica (1997) vol. 70, pp. 77-88 | Full text
Abstract
The paper analyses long-term variability in the number of days with precipitation in Kraków in relation to changes in atmospheric circulation. Data on annual, semi-annual and seasonal numbers of days with precipitation > 0.1 mm in the 1814-1995 period and data on days with precipitation >1.0 mm and > 10.0mm for the years 1850-1995 were used. For precipitation threshold values, averages, maxima, minima, standard devia-tions and variability coefficients are presented. For the 1874—1995 series, correlation coefficients between the number of days with precipitation and the index of cyclonicity - C, determined on the basis of the classification of circulation types proposed by T. Niedźwiedź, are calculated. It was found that the number of days with precipitation >0.1 mm and > 1.0 mm shows significant positive trends in the cold half of the year and in the winter period, and negative trends in the warm half of the year and in the summer period. The variation in the number of days with precipitation >0.1 mm and >1.0 mm shows significant correlation with fluctuations of the C index which is most pronounced in the cold half of the year.
Keywords: variability, trends, number of days with precipitation, atmospheric circulation, Kraków
[r.twardosz@uj.edu.pl], Department of Climatology, Institute of Geography of the Jagellonian University ul. Grodzka 64, 31-044 Kraków, Poland