摘要：This article presents the results of studies conducted on the variability of thermal and precipitation conditions in Poland in the second half of the 20th century, especially taking into consideration periods which were unfavorable for agricultural production. Averaged spatial temperatures and precipitation totals from consecutive years 1951 to 2000 were used. A significant increase in spring temperatures was noted, while the winters also became warmer. This had a significant effect upon the change of the thermal vegetation period’s duration. No changing trends were noted with regard to the amount of precipitation.The analysis of the seasonal structure during the anomalous years, with regard to temperature and the amount of precipitation, made it possible to pinpoint years particularly unfavorable for agricultural production. There was a certain repeatability of unfavorable conditions, tied to the existence of a relatively stable 8-year cycle of temperature change, which was especially noticeable during the wintertime. During the last two decades of the 20th century, high temperature values, occurring also in the summertime, in combination with insufficient precipitation, contributed to the occurrence of dry spells and even periods of drought. The occurrence of dry spells during the vegetation period and the extreme shortening of the vegetation period have a significant effect upon the amount of grain crop production.
关键词：air temperature ; atmospheric precipitation ; variability ; crop production ; Poland
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