Thunderstorms, particularly air mass thunderstorms, are often short-lived because they essentially rain themselves out of their moisture supply.
Here's a breakdown:
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Limited Moisture Supply: Air mass thunderstorms rely on local, unstable air and moisture. Once the storm begins to precipitate, it quickly depletes the available moisture in its immediate vicinity.
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Outflow Boundaries: As the thunderstorm produces rain, the cool, dense air descends, creating an outflow boundary at the surface. This outflow boundary can cut off the inflow of warm, moist air that is needed to sustain the storm.
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Rain-Cooled Air: The downdraft of rain-cooled air suppresses the updraft (the rising air that fuels the storm), weakening the thunderstorm's intensity. The updraft is crucial for lifting warm, moist air to higher altitudes where it can condense and form more precipitation. When the updraft weakens, the storm dissipates.
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Self-Destructive Cycle: In essence, the thunderstorm creates conditions that lead to its own demise. The rainfall and resulting outflow boundary disrupt the very conditions necessary for its continued existence.
In summary, air mass thunderstorms are short because they lack a continuous supply of moisture and are disrupted by their own outflow and rain-cooled air. This cycle limits their lifespan to relatively brief periods.
