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vol. 9, nr. 2 (2007)
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Characteristics of turbulence on the basis of wind speed in the region of Stargard Szczeciński
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Małgorzata Czarnecka, Jadwiga Nidzgorska-Lencewicz
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Department of Meteorology and Climatology, Agricultural University
ul. Papieża Pawła VI, 3; 71-434 Szczecin |
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vol. 9 (2007), nr. 2,
pp. 321-332
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abstract:
The basic material comprised the results of temporary measurements of wind speed and direction at the height of 2 metres above sea level, recorded every hour at the automatic station in Lipki near Stargard Szczeciński during 1995-2005. For the evaluation of the turbulence value, Parczewski's classification was used. According to this classification, the classes of turbulence , i.e. weak, moderate, strong and very strong, are determined by the following threshold wind speeds: 0, 3, 4, 10 and 20 m s(-1). In the analysed period of 11 years, the dominating class was the weak turbulence, resulting from the occurrence of winds of speeds below 4 m s(-1), recorded at different directions of the wind. During a year, the frequency amounted to nearly 70%, and during a calendar year it was even about 85%. During winter, weak turbulence occurred almost twice as often in the night than in the daytime, whereas during summer it was the opposite. Moderate turbulence occurred incomparably more rarely - in a period of a whole year only in 15% of cases, mainly associated with western and southern winds. It was observed that the best natural air ventilation occurred during calendar spring in the daytime, and particularly from noon to sunset, i.e. from 12 (midday) to 16 p.m., whereas the worst natural air ventilation was during calendar summer, in the night, particularly from 1 a.m. to 5 a.m.
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keywords:
turbulence classes, wind directions, seasons of the year, periods of day (24 hrs), time of day, frequency, lack (calm), weak turbulence, moderate turbulence
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original in:
Polish
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