Санкт-петербург
he climate of St. Petersburg is temperate and humid, the transition from marine to continental. The region is characterized by frequent changes of air masses, largely due to the cyclonic activity. In the summer the prevailing westerly and North-westerly winds in winter West and South-West.
Petersburg weather stations have data from 1722. The highest temperature recorded in St. Petersburg for the whole observation period, +37,1 °C[2], and the lowest -35,9 °C.the climate is temperate in Petersburg, the transition from temperate to continental temperate Maritime. This type of climate is explained by the geographical position and atmospheric circulation characteristic of the Leningrad region. This is due to the relatively small number of arriving at the earth's surface and in the atmosphere the sun's heat[1].
Due to the small amount of solar heat moisture evaporates slowly. The total inflow of solar radiation here is 1.5 times less than in the South of Ukraine, and twice less than in Central Asia. For the year in St. Petersburg is on average 72 Sunny day. Therefore, throughout the greater part of the year is dominated by the days with cloudy and overcast weather, the scattered light[1]. Length of the day in St. Petersburg varies from 5 hours 51 minutes on the winter solstice to 18 hours and 50 minutes during the summer solstice. In the city there are the so-called "white nights", the upcoming may 25-26, when the sun sinks beyond the horizon of not more than 9°, and the twilight practically coincide with the morning. The white nights end on July 16-17. In total, the length of the white nights more than 50 days[3]. The annual amplitude of the amounts of direct solar radiation on a horizontal surface under a clear sky from 25 MJ/m2 in December to 686 MJ/m2 in June. Cloudiness decreases in average for the year coming total solar radiation by 21 %, and direct solar radiation by 60 %. Average annual total radiation 3156 MJ/m2[4]. The number of hours of sunshine - in the year 1628