anticyclones
An Anticyclone is a large-scale circulation of winds around a central region of high atmospheric pressure.
Anticyclones appear on weather charts as a series of concentric, widely spaced isobars of 1000 mbs and aboThe anticyclone on the other hand is produced by a large mass of descending air. ve.
Causes of anticyclones;
1. Poleward movement of high pressure cells – here, were the Hadley cell meets the Ferrel cell at 30°N or S the high pressure zone can move, creating high pressure in higher latitudes. In Britain this North African High can bring heat waves
2. Thermal or cold anticyclones are typical of continental INTERIORS and hence are less likely in the British isles. In cold polar regions or during winter at lower latitudes, the land cools very rapidly (since there is no moderating influence of the sea), chilling the air above. This radiational cooling (with temperatures as low as -40°C in Siberia!) causes the air above to contract and sink to the ground, raising the air pressure and reducing the likelihood of cloud formation
3. Convergence in the Polar Front Jet Stream – The PFJS is found 9 to 12km up in the Troposphere and meanders at different latitudes in waves known as Rossby waves. Here, the air moves in balance with lots of forces and is caused by different pressures, so moves according the Pressure Gradient Force. However, the Coriolis Force deflects the wind that is caused by Pressure gradients, so the net result is an upper level wind that blows parallel to the isobars, known as the Geostrophic wind or our jet stream. This jet stream meanders from latitude to latitude which introduces another force, the Centrifugal force. Here, centrifugal force around a ridge in the Rossby waves causes the air to speed up, and in the troughs it slows down. Where the air slows down going into the Trough and just out of the ridge it builds up, and much of this air is forced to sink to the surface causing HIGH PRESSURE or an anticyclone.
Anticyclones appear on weather charts as a series of concentric, widely spaced isobars of 1000 mbs and aboThe anticyclone on the other hand is produced by a large mass of descending air. ve.
Causes of anticyclones;
1. Poleward movement of high pressure cells – here, were the Hadley cell meets the Ferrel cell at 30°N or S the high pressure zone can move, creating high pressure in higher latitudes. In Britain this North African High can bring heat waves
2. Thermal or cold anticyclones are typical of continental INTERIORS and hence are less likely in the British isles. In cold polar regions or during winter at lower latitudes, the land cools very rapidly (since there is no moderating influence of the sea), chilling the air above. This radiational cooling (with temperatures as low as -40°C in Siberia!) causes the air above to contract and sink to the ground, raising the air pressure and reducing the likelihood of cloud formation
3. Convergence in the Polar Front Jet Stream – The PFJS is found 9 to 12km up in the Troposphere and meanders at different latitudes in waves known as Rossby waves. Here, the air moves in balance with lots of forces and is caused by different pressures, so moves according the Pressure Gradient Force. However, the Coriolis Force deflects the wind that is caused by Pressure gradients, so the net result is an upper level wind that blows parallel to the isobars, known as the Geostrophic wind or our jet stream. This jet stream meanders from latitude to latitude which introduces another force, the Centrifugal force. Here, centrifugal force around a ridge in the Rossby waves causes the air to speed up, and in the troughs it slows down. Where the air slows down going into the Trough and just out of the ridge it builds up, and much of this air is forced to sink to the surface causing HIGH PRESSURE or an anticyclone.