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Which of the following is a possible consequence of subsidence?
  • A
    Wide spread NS and AS clouds and intense precipitation.
  • B
    Clear air turbulence at higher altitudes.
  • C
    CB-clouds and thunderstorms over a large area.
  • D
    An inversion over a large area with haze, mist.

Refer to figure.

SUBSIDENCE is related to a HIGH PRESSURE SYSTEM/ANTICYCLONE.
Within an anticyclone, at high altitude we have air converging, then descent of air within the anticyclone (subsidence) and divergence at the surface. Typical weather in an area under the influence of a High-Pressure is clear skies due to the sinking motion of air (subsidence), lighter winds than around a Depression and reduced chance of precipitation.

Weather associated with High Pressure Systems:

  • Summer (and cold high pressure systems in winter):

- CLOUD: none except on the edge of the anticyclone
- PRECIPITATION: none
- VISIBILITY: Generally moderate with haze
- TEMPERATURE: Dependent on type
- WINDS: Light

In a High Pressure system, air descends at the centre. As the air descends it will be heated adiabatically and will be warmer than the air at a lower level. This is called a Subsidence Inversion.

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