SME
Meteorology · Problem type
Stable or unstable air
Use this for “The air cools 7.5 °C per km above the ground. Is it stable, conditionally unstable or unstable?”
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How does a lifted parcel behave in this air?
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Compare the air’s lapse rate with 9.8 °C/km (dry) and about 6 °C/km (saturated).
Assumptions
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A lifted parcel cools 9.8 °C per km while dry and about 6 °C per km once saturated.
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Air whose temperature falls more slowly than the parcel’s leaves the parcel colder and heavier, so it sinks back.
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The environment’s lapse rate is how fast the surrounding air cools with height; an inversion warms instead.
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Atmospheric thermodynamics
Main lesson
The lifting condensation level
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