This paper presents the state of research regarding extreme phenomena at different spatial scales in Polish scientific publications ( mainly climatological ones ). The analysis covered papers concerning: various classifications and criteria for the identification of extreme phenomena, characterising the causes and effects of extreme phenomena, modeling and forecasting of extreme phenomena as well as using the knowledge about extreme phenomena in practice. The review of literature on extreme weather and climate phenomena allowed the authors to see a large number of problems connected with the research upon extreme phenomena. Problems concerning definitions, research methods and extreme phenomena forecasting were mainly dealt with in the paper. The effects of occurrence of hydrometeorological extreme phenomena are an issue of significant importance.

The aim of the paper is to review the state of research on the phenomenon of derecho, with particular emphasis on studies conducted in Europe and on the American continent. The paper presents different approaches to the identification criteria of derecho. The structure and conditions for its formation were characterized. Long-term studies on the multi-annual occurrence of derecho on both continents were described. The presented review of literature led to the conclusion that there are still many opportunities to study mesoscale convective systems which cause derecho on the European continent

Wind gusts are a dangerous meteorological phenomenon which may cause material damage and risk to human life. In recent years they have been observed more frequently. The purpose of this analysis is to examine synoptic situations favouring the occurrence of wind gust in Żeńsko (Western Pomerania ) and to characterize their seasonal, monthly and diurnal variations. The study uses data on wind speed and direction from the wind data collection tower at Żeńsko from the period between January 2008 and December 2009. Wind speed was measured at two heights – 25 and 50 m above ground level. The location selected for this analysis represents lakeland landscape, typical for this part of Poland. Wind Gusts at Żeńsko are observed throughout the year. The maximum of their occurrence is observed in March and August, while the minimum in May and September. During the day they most often occur in the afternoon hours. A synoptic situation favouring the occurrence of wind gusts is a baric col over Poland. They equally often occur during fronts transition, particularly with a cold front. The investigation revealed that wind gusts always occur on days with the advection of more than one air mass. They also occur with a high probability (over 25%) in the cases of tropical and polar continental air flow.

The paper analyzes winter temperatures in the Polish part of the southern Baltic coast using the mean monthly temperature from the years 1951–2010 from the following stations: Szczecin, Świnoujście, Ustka, Hel, Gdynia and Elbląg and the maximum daily air temperature from the years 1986–2010 from the stations: Szczecin, Świnoujście, Kołobrzeg, Łeba and Hel. In order to characterize the circulation determinants in especially warm winters, the NAO index and types of circulation according to Lityński were used. The study showed a strong influence of the western airflow on winter temperatures, which distorted the upward trend in temperature by an extremely high intensity of advection. The particularly strong advection of air masses from the Atlantic in the last decade of the twentieth century contributed to the high, compared to other years, winter temperature on the Polish coast, especially in its western part

Extreme cases of singularities in the annual course of air temperature in Krakow in the period 1826–2010

The aim of this study is to identify extreme cases of the appearance of singularities in the annual air temperature course in the period 1826–2010 in Krakow. In climatological literature the term “singularities” denotes characteristic fluctuations in the annual course of temperature, occurring periodically every year. In this paper a special attention was paid to the duration and long-term variability of distinguished singularities. A 5-degree polynomial was used to smooth out the annual course of temperature. A model of temperature variation was calculated on this basis. Differences between the mean daily temperature values and those calculated from the model was taken into account to distinguish these singularities. It was found that in the period 1826–2010 in Krakow, warm anomalies slightly prevailed over cold anomalies. In the annual course, singularities occurred most frequently in spring, but the greatest differences between the daily mean air temperature and that calculated from the model appeared in winter. However, there was no clear recurrence of the analyzed events (singularities) in the multi-year period.

In spite of the fact that cloudiness is not a direct reason of extreme meteorological events, it is a visual indicator of atmospheric conditions influencing the formation of other meteorological elements. It can also help in forecasting and explaining meteorological phenomena. In this paper selected characteristics of cloudiness in periods with anomalous and extreme amount of cloudiness at three synoptic stations in the western part of Polish Carpathians were analyzed. Months with anomalous and years with extreme amount of cloudiness were taken into account. Records of cloudiness  observations in the years 1971–2000 at selected synoptic stations of Institute of Meteorology and Water Management ( Bielsko-Biała, Kasprowy Wierch, Zakopane ) were used in this analysis. Data from the Calendar of synoptic situations for Southern Poland by Niedźwiedź (2011) regarding circulation patterns and air masses from the appropriate period were used as well. This analysis indicated a distinct influence of atmospheric circulation on the occurrence of anomalous amount of cloudiness and some modifications of this influence by local conditions. It also showed differences between the processes that form anomalous amount of cloudiness at different locations in the analyzed mountain area.

The paper discusses cloudiness in the context of the occurrence of extreme events using records from Krakow ( 1951–2012 ). The variables analysed included the maximum cloud cover, the number of cloudy and overcast days, and the structure of cloud cover. The study also analysed the numbers of days with the Cumulonimbus cloud and a thunderstorm in Krakow and its environs using data from the stations at Gaik-Brzezowa and Łazy ( 1991–2012 ). The number was found to have increased, especially in the cool half of the year, which may be related to the current climatic warming. However, the increase in the number of days with a thunderstorm was greater than in that with the Cumulonimbus cloud.