The ongoing climate warming affects, among others, and the variability of thermal conditions in spring and autumn are resulting in earlier dates of the beginning and end of the growing season. The present paper provides detailed characteristics of the phenomenon of ground frosts, addressing the question of whether the risk of frost-related damage in the extending growing season is still present. The assessment of temporal and spatial distribution of ground frosts (5 cm above ground level-AGL) in Poland in the thermal growing season (AT > 5 °C) was conducted on the basis of the results of air temperature measurements at 5 and 200 cm a.g.l. obtained from 52 station of the Institute of Meteorology and Water Management—National Research Institute for the period 1971–2020. The thermal growing season was calculated using the method by Gumiński. The following were calculated: the dates of the occurrence of ground frosts in spring and autumn, duration of the frost-free period, the number of days with frosts of various intensity, according to years, ten-day period and days in a year together with trends of change. The conducted analysis demonstrated that the number of days with frosts in the thermal growing season in the multiannual period under analysis (1971–2020) does not show any statistically significant changes. It was found that in the thermal growing season, the average number of days with ground frosts in Poland amounts to 28 and ranges in spring from 15 to 22, and in autumn from 8 to 12. Most frequently, approx. 49%, slight frosts are recorded, followed by moderate (29%), severe (15%) and very severe (7%). A positive effect of water reservoirs on decreasing the frequency and intensity of frosts, as well as sporadic occurrence of the phenomenon in the second half of June were demonstrated. Statistically significant earlier dates of disappearance of frosts in spring, later dates of occurrence in autumn and the lengthening of the frost-free period from approximately 2 days in the north-east of Poland to approximately 8.0 days over 10 years in the Pomerania region, create increasingly more favourable conditions for the cultivation of plants with high thermal requirements in Poland.

Frosts cause damage to plants in field crops and also trees, thus contributing to heavy economic losses in agriculture. One of the consequences of climate warming is the lengthening of the thermal growing season (AT > 5 °C) and acceleration of phenological phases as well as the lengthening of the frost-free period. This favourable element allows the extension of the range of cultivated plants to include plants requiring warmth and a longer development period. The present study concerns the area of Poland. The data on mean and minimum 24-h period air temperature (200 cm above ground level—AGL) were obtained from 52 meteorological stations of the Institute of Meteorology and Water Management—National Research Institute (IMGW-PIB) for the period 1971–2020. A day with air frost was identified when the recorded minimum air temperature was below 0.0 °C and the mean 24-h period air temperature was above 0.0 °C. All calculations concerning frosts were limited to the period with mean 24-h period air temperature >5 °C (the growing season) as determined with the Gumiński method. The obtained results show that in the thermal growing season (AT > 5 °C) in Poland, no statistically significant change in the average number of days with air frosts in the period 1971–2020 was found. On average, in Poland, in the years 1971–2020, a lengthening of the thermal growing season by 6.2 days over 10 years was identified. Earlier disappearance of the latest air frosts in spring was identified as 2 to 3 days over 10 years, and the later occurrence of air frosts in autumn as 1 to 4 days over 10 years. The share of severe (−4.1°C ÷ −6.0 °C) and very severe (<−6.0 °C) frosts in the total number of days with air frosts in Poland amounts to, on average, 5.8% in spring and 2.6% in autumn.

The quality of a given bioclimate is much affected by the atmospheric environment (taken to include solar radiation, air temperature and humidity, atmospheric pressure, wind speed and levels of atmospheric pollution), as well as by geographical factors relating to topography and cover, the drainage system and land use (Owczarek 2009, Czarnecka, Nidzgorska-Lencewicz 2010, Koźmiński, Michalska 2011, Owczarek 2012). Tourists staying in a coastal area must contend with considerable variability of weather from one day to another, or even hour by hour, in the cold half-year in particular. Changes of weather have a profound effect on the human organism, inter alia giving rise to migraines, sleep disturbances and hypersensitivity. The work described here sought to assess temporal (inter alia seasonal) and spatial variability to heat loading of the human organism characterising the Polish Baltic coastal zone, as well as the temperature of water by beaches. It was to achieve this kind of assessments of bioclimate and its impact on the human organism that the index known as the UTCI (Universal Thermal Climate Index) was devised, taking in air temperature, wind speed, air humidity and absorbed solar radiation (expressed as mean radiant temperature) (Błażejczyk & Kunert, 2011). This index represents objective changes in physiological parameters of the human organism occurring thanks to differing environmental conditions as determined in relation to a 10-point scale for heat loading of the human organism (°C) that translate into descriptive terms ranging from extreme heat stress to extreme cold stress. UTCI values referred to here were calculated using BioKlima 2.6 software - http://www.igipz.pan.pl/Bioklima-zgik.html. Six zones for the heat loading of the human organism found to be present along the Polish coast during the four seasons of the year were designated by summing the frequency of occurrence of days with a particularly stimulating effect, be this severe or very severe heat stress or severe, very severe or extreme cold stress. The UTCI-based analysis sustained conclusions as follows: - The Polish Baltic coast is found to be characterised by marked day-to-day variability in the heat loading of the human organism, particularly in the November-late May period, with the result being a significant “nuisance” represented for tourists. - Along the western part of the coast and in the area of the Bay of Puck, conditions thermoneutral for the human organism were found to dominate (accounting for more than 60% of the days in a month) over the whole period from May through to mid-October. In the case of the northern part of the coast from Darłowo to Łeba the same was found to be true of the period extending from June through to the middle ten-day period of September, creating conditions favourable for outdoor recreation. - The duration of the bathing season with mean monthly water temperatures ≥18°C is of approximately 45 days along the coast from Darłowo to Łeba, 46-50 days in the central part of the coast, 46-60 days in the area of the Bay of Gdańsk and 61-70 in the area of the Bay of Pomerania. In most years under analysis, there was no identification of a bathing season with mean monthly water temperature ≥18°C in the Kołobrzeg and Władysławowo areas. - The bioclimatic conditions most favourable for recreation and tourism were identified for the area of the Bay of Pomerania, followed by the Bay of Gdańsk. Less-favourable conditions characterise the central part of the coast, while the least favourable circumstances extend through the northern area from Darłowo to Łeba, in which the bioclimate’s stimulatory effect is strongest.- The high spatial variability characterising heat loading of the human organism that it proved possible to identify for the Polish coast offers the possibility of particular regions and seasons being selected for recreation, in relation to tourists’ health status and specific requirements.

Abstract. The analysis is based on the materials published by the Statistical Office in Szczecin for 2000-14, presented on a monthly basis, concerning the total number of tourists (including foreign tourists) and the overnight stays. The distribution of the number of tourists and their accommodation per month and season was correlated with mean monthly values for air temperature, cloudiness and wind speed. Meteorological data for the period 2000-14, as averaged for the whole voivodeship, was obtained from four IMGW stations (Świnoujście, Koszalin, Szczecin and Szczecinek). Statistical analysis was conducted and time trends of the number of tourists and overnight stays were identified for individual months with the use of linear and polynomial regression. The seasonal nature of tourist flows was assessed by the number of tourists and accommodation provided for tourists in summer compared to winter, and spring to autumn. Air temperature and cloudiness were found to have the greatest effect on the uneven distribution of tourist numbers across a year. Each year, approximately 1.7 million tourists visit Zachodniopomorskie Voivodeship, 1

The ongoing global warming promotes an expansion of the areas of land already used for viticulture, as well as the establishment of new vineyards in areas that were previously considered unsuitable. In this study, a temporal and spatial assessment of the thermal conditions for viticulture in Poland was conducted using a series (1971–2019) of daily data on air temperature (mean, maximum and minimum) obtained from 52 stations of the Polish Institute of Meteorology and Water Management—National Research Institute. On the basis of the values of air temperature for the year (January–December), the vegetative period (April–September), and July, as well as the duration of the period of active growth of the plant (air temperature >10 °C) and the sum of active temperatures (SAT) in this period, five potential areas for viticulture in Poland were identified with respect to thermal conditions. It was found that approx. 60% of the country’s area shows conducive and moderately conducive conditions for intense viticulture. In the analysed multiannual period, there is a dynamic increase in air temperature in Poland, an increase in the sums of active temperatures (SAT) as well as an increase in the duration of the period of active growth of the plant. The ongoing global warming causes a shift of the current boundary of intense viticulture to the north of Poland (from 100 to 150 km). The greatest increases in air temperature and SAT values were found in the south-west and west of Poland, with a marked decrease shown towards the north-east and east.

Słowa kluczowe wskaźniki, liczba turystów, noclegi, obszary sezonowości Streszczenie W celu określenia nieregularności ruchu turystycznego w Polsce w latach 2004-2014 posłużono się danymi GUS -miesięcznymi dotyczącymi liczby turystów ogółem, w tym krajowych i zagranicznych, oraz udzielonych im noclegów w 16 województwach. Na ich podstawie obliczono wskaźnik sezonowości liczby turystów z okresu lata do zimy (S lz ) i jesieni do wiosny (S jw ) oraz udzielonych noclegów z okresu lata do zimy (SN lz ) i jesieni do wiosny (SN jw ), a także współczynnik zmienności (W %) w ciągu roku. Nieregularność ruchu turystycznego najwyraźniej zaznacza się w województwach północnej Polski, w tym w strefie wybrzeża i na pojezierzach, gdzie liczba turystów latem jest 3-4 razy większa niż zimą, a liczba udzielonych noclegów nawet 5-7 razy większa. W miarę przemieszczania się w głąb kraju maleje wielkość sezonowości, przyjmując w jego środkowej części najniższe wartości wskaźników dla liczby turystów krajowych S lz (iloraz liczby turystów z okresu lata do zimy) i udzielonych noclegów SN lz (iloraz liczby noclegów z okresu lata do zimy) -poniżej 2, a dla turystów zagranicznych -poniżej 3. W latach 2004-2014 w większości województw występuje ujemny, istotny lub wysoce istotny statystycznie trend wskaźnika sezonowości liczby turystów (S lz ). Uwzględniając wartości wskaźni-ków sezonowości dla liczby turystów (S lz ) zarówno krajowych, jak i zagranicznych oraz udzielonych im noclegów (SN lz ), jak również współczynnika zmienności (W %) liczby turystów w roku, wydzielono na terenie kraju 5 obszarów o różnej sezonowości ruchu turystycznego: nadmorski, pojezierny, nizinny-wielkomiejski, wyżynny i górski. WprowadzenieWszystkie destynacje na świecie stoją przed problemem sezonowości. Jest ona zjawiskiem niekorzystnym, oddziałuje na wszystkie elementy rynku turystycznego, zarówno po stronie popytu, jak i podaży (Borzyszkowski, 2014). W Polsce sezonowość ruchu turystycznego uwarunkowana jest głównie klimatem oraz przebiegiem pogody w ciągu roku, zwłaszcza czasowym rozkładem

Na większości badanych jezior średnia miesięczna temperatura wody w najcieplejszym miesiącu-lipcu wynosi od 21,0° do 22,0°C-to wartości wyższe o około 2,0°C w porównaniu z temperaturą powietrza. Średni potencjalny sezon kąpielowy z temperaturą wody 18°C-trwa od 76 do 100 dni, a z temperaturą wody 20°C-od 50 do 70 dni. Najkorzystniejsze warunki termiczne do kąpieli na jeziorach występują na Pojezierzu Lubuskim oraz w południowo-zachodniej części Pojezierzy Pomorskiego i Mazurskiego, a mniej korzystne na Pojezierzu Kaszubskim i Pojezierzu Suwalskim.

Zarys treści. Wykorzystując dobowe wartości ciśnienia atmosferycznego sprowadzonego do poziomu morza z 29 stacji meteorologicznych IMGW, za lata 1986-2010, opracowano czasowy i przestrzenny rozkład międzydobowych zmian ciśnienia >8 i >12 hPa na terenie Polski. Oceniono częstość występowania zmian ciśnienia z doby na dobę w półroczach chłodnym i ciepłym oraz wielkość międzydobowych wzrostów i spadków ciśnienia >8 hPa. W kolejnym etapie pracy wyodrębniono ciągi trwające 2, 3, 4, 5 i więcej dni ze zmianami >8 hPa. Przeprowadzona analiza dała podstawę do wydzielenia na terenie Polski dwóch stref i jednej podstrefy o zróżnico-wanej uciążliwości dla organizmu człowieka, powodowanej dużymi międzydobowymi zmianami ciśnienia atmosferycznego w chłodnej połowie roku. W miarę przemieszczania się z południa na północ kraju wzrasta częstość i wielkość zmian ciśnienia z doby na dobę, zwłaszcza w zimie. W tej porze roku notowane są większe spadki aniżeli wzrosty ciśnienia, a ekstremalne zmiany z doby na dobę przekraczają 35 hPa. Udział międzydobowych zmian ciśnienia >8 hPa w ogólnej liczbie dni półrocza chłodnego wynosi od poniżej 23% na południu do ponad 25% na północy Polski.Słowa kluczowe: ciśnienie atmosferyczne, międzydobowe zmiany >8 i >12 hPa, rozkład czasowy i przestrzenny, strefy uciążliwości. WstępOrganizm człowieka jest bardziej wrażliwy na zmiany ciśnienia atmosferycznego w krótkim czasie aniżeli na jego aktualną wielkość. Wzrosty i spadki ciśnie-nia atmosferycznego przeważnie zapowiadają zmiany warunków pogody, to jest temperatury i wilgotności powietrza, zachmurzenia, opadów, prędkości wiatru http://dx