Temperatura powietrza w dniach „zimnych ogrodników” w okolicy Lublina

Józef Kołodziej

Krzysztof Liniewicz

Hanna Bednarek

Abstrakt

The paper concerns characterization of minimum air temperature values – at the height of 5 and 200 cm – measured within 24 hours and values of an average air day temperature at the height of 200 cm above the ground. Results of the measurements come from the Agrometeorological Observatory in Felin at the Department of Agrometeorological AR in Lublin. The paper presents the materials which were gathered between 1951 and 2000 concerning four days of May (12–15), that is the period called „cold gardeners”. The aim of the paper was characterization of the thermal proportions in these days and verification whether the common opinion of colder weather finds confirmation in the values of minimum and average temperatures. The material was analysed by means of the basic descriptive statistics and classified in the resolute series of the width of 2°C each, right-handedly shut which enabled to determine which values of minimum temperature occured most often in the four days of May. Between 1951 and 2000 in Felin the minimum sub-zero temperature at the height of 5 cm occured within eight years in thirteen cases, that is with the frequency equal to 6.5%. Mostly, i.e. in six years, the minimum sub-zero temperature was noted on 13th May. At the height of 200 cm above the ground the minimum sub-zero temperature was noted during three years, mostly–twice–also on 13th May. The lowest minimum sub-zero temperature that was ever determined in the analysed period is – 4.6°C near the ground on 13th May 1978. At the height of 200 cm the lowest temperature – equal to 1.7°C – was noted on 14th May 1980. The values of minimum temperature at the height of 5 cm, which were noted mostly, fit in two classification divisions (4–6 and 6–8°C). 50 and 37 cases were noted, which means the frequency of 43.5% in the test of 200 repetitions. At the height of 200 cm the most numerous values of minimum temperature were noted in four classification divisions. These records occurred 123 times (61.5% of the whole test), mostly in the range of 6–8°C – in 36 cases. Among the most numerous values of day averages a shift towards higher temperature can be clearly seen. In five classification divisions 82 cases (41% of the test) were determined. The occurrence of extreme values of minimum temperature clearly depended on the type of air masses which were above Poland in a particular situation. When the lowest temperature occurred the presence of arctic masses (sea or old) was ascertained, the occurrence of the maximum temperature was connected with polar (mostly sea masses) and even tropical masses. On the basis of numerous articles from literature it can be stated that the damage in soil cultivation is caused not only by the drops of temperature below zero, temperatures slightly above zero have also detrimental effects, which cause thermal stress, and as a consequence fungi diseases and a considerable drop in crop yields. In Felin between 1951 and 2000 such temperature was noted many times during the „cold gardeners” period.