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In wintertime stratus is often formed when warm maritime air moves over cold land. How can such clouds be classified?
  • A
    Frontal clouds.
  • B
    Convective clouds.
  • C
    Turbulence clouds.
  • D
    Orographic clouds.
Processes that increase atmospheric stability:
  • Cold air moving at low levels – warm air aloft.
  • Stability increases when lower layers are cooled/Upper layers are warmed.

Warm air moves over cold land” => describes a stable layer.

TURBULENCE CLOUDS. Formed in stable air conditions, where the vertical movement of air is limited. The cloud will tend to develop horizontally, giving layers of ST/SC.

    • Stratus formed by turbulence will occur in the friction layer when mixing occurs by turbulence and the condensation level is situated below the top of the turbulent/friction layer.
  • warm maritime air” => humid air mass. The rising air is likely to reach the dew
    point before it reaches the top of the friction layer and a cloud will form.
Note:
“Orographic clouds” INCORRECT. They are formed when air meets a ridge and is forced to rise – which is not the case.
“Convective clouds” INCORRECT. These are formed in unstable air conditions – forming CU type clouds.
“Frontal Clouds” INCORRECT. These are caused by widespread lifting caused by a front (warm air meets cold air) – such situation isn’t described in the question text.

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