2. Atmospheric circulation

The European atmospheric centres of action, extensive and almost stationary low or high pressure areas which control the movement of atmospheric disturbances over the Europe. They influence the weather during the seasons.

The most prominent in the territory of the Czech Republic are:

  • marine polar air = Icelandic Low - year-round effect, cold rainy winter, rainy cold summer
  • continental polar air from the Russia = Siberian High -  year-round effect, more intense in winter (dry, freeze), warm dry summer
  • tropical marine air from the Azores Islands = Azores/Bermuda High - year-round effect, more often in summer (warm, storms), warm sunny winter (thaw)
  • continental tropical air = Iranian Low - occasionally in summer, warm and dry (Indian summer)
  • arctic air -possible all year round, oceanic (snow, cooling) or continental (rapid cooling, dry)
  • equatorial air - exceptionally

The position of the polar front is key for the weather in the Czechia. The polar front is the boundary between polar and tropical air masses. The polar front changes its position almost every 5-7 days, which means that the weather changes every 5-7 days.

polar front
Fig. 1. Position of the polar front in summer and winter. The Czech area is influenced by the warm tropical air during the summer and by the cold polar air during the winter.