GEOG 1101 Lecture Notes - Lecture 5: Fluid Parcel, Lapse Rate
7 Feb 2017
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Document Summary
Atmospheric stability refers to the tendency of an air parcel wit its water vapor, to either remain in place or to change vertical position by ascending (rising) or descending (falling). * a stable parcel of air resists vertical displacement or, when disturbed, tends to return to its starting place. * an unstable parcel of air continues to rise until it reaches an altitude where the surrounding air has a density & t similar to its own. Rules of stability: when an air parcel is warmer (less dense) than the surrounding air, the parcel will rise: The actual t lapse rate in the lower atmosphere at any particular time under local weather conditions is the elr. Stable condition exist when the elr < dar. * this usually results in no uplift of air, and may bring about subsidence or sinking of the air parcel. * high pressure cells form stable atmospheric conditions.
