This study compares the potential annual energy absorption of a flat-plate solar collector at different tilt angles in Poland. Optimal tilt angles were tested in three variants: over the course of the year, in fall/winter and in spring/summer. The results were compared with automatically tracked collectors where the active surface is perpendicular to the angle at which solar radiation reaches the collector. The results were simulated based on the meteorological data. A comparison of the energy outputs of solar collectors in optimization variants 1, 2, and 3 indicates that variant 1 produces the highest energy output.

Abstract. The article contains descriptive statistics on rainfall in an area of the southern part of the last ice age in Europe, and which now comprises the north-eastern part of the Poland. The study covers the period of 1981-2010.The sums of the annual and monthly precipitation were calculated, while years and months were evaluated in relation to the multi-annual and monthly averages. The frequency of daily precipitations was also determined. Values of SPI (Standarized Precipitation Index) were calculated together with the values of the Selianinov Index, which measures the environmental aspect of precipitation.The average annual rainfall showed a spatial heterogeneity in the region from 700.1 mm (Elblag in the north-west) to 555.3 mm (Mława) in the east and south-east. The greatest precipitation occurred in the last decade of the analysed period of thirty years. However, statistical analysis shows no significant trend change in precipitation during this period. The number of years with sums of precipitation below 75% of the normal turned out to be very small. In the annual cycle, summer precipitation prevailed. On a monthly basis, the averages sometimes exceeded the multiyear averages by as much as 200%, while extreme lows in monthly precipitation reached levels below 25% of the long-term averages. The calculated value of the SPI indicated that the most common drought conditions occurred in May and June; such droughts did not occur in April and July. The Selianinov Index indicates that the least favorable hydrothermal conditions occur in April and May, while the most favorable conditions occur in August and September.

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Aim of the study. Indication of changes in maize yield for grain and silage in connection with the observed climate changes. Material and methods.Data from field experiments of the experimental station of the University of Warmia and Mazury since 1972 as well as meteorological data (air temperatures and precipitation). Calculations using the trend analysis of original variables and determined indexes (GDD, SPI, Sielianinov index), weather-yield linear models and elements of spectral analysis. Results and conclusions. Changes in thermal conditions were demonstrated based on average air temperatures and the GDD index. There were no significant changes in atmospheric precipitation, showing a small periodicity of ten years, and no changes in monthly frequency with a deficit of precipitation (SPI analysis). It was demonstrated that changes in thermal conditions as well as the introduction of new maize varieties over fifty years significantly improved plant maturation, which resulted in a significant increase in grain weight. However, this did not affect the yield of maize for silage, neither in crop rotation nor in the monoculture system.

Between 01.01.2010 and 31.12.2011, we conducted measurements of air temperature and relative humidity at points located deep within forest area, along the edge of the forest in the immediate vicinity of a lake and in open terrain. The thermal and humidity conditions that have a stimulating effect on human well-being were determined for the selected locations by calculating the number of hot (tmax ≥ 25°C) and very hot days (tmax ≥ 30°C) as well as the number of frosty (tmax < 0°C) and very frosty days (tmin ≤ −10°C). The range of the stimulatory effect on human well-being by temperature was determined based on changes in the average night temperature and the amplitude of the daily air temperature. Stimulating humidity conditions were determined by comparing the the relative humidity to a reference value associated with a moist feeling and calculating the number of humid days (s ≥18.8 mbar).