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Instruments Used to Monitor Atmospheric Instability

Atmospheric stability is related to the motion and saturation of air parcels. Overly active and saturated air parcels are less stable, and can be monitored primarily using instruments that measure atmospheric pressure. Atmospheric pressure, in turn, is related to its temperature and stability. Methods -- measuring and combining different atmospheric qualities -- is another way to monitor the atmosphere's stability.

  1. Atmospheric/Barometric Pressure

    • Atmospheric, or barometric, pressure is measured as the pressure or weight of air above a certain location. The pressure is related to the density of the air and also the weather conditions. Higher pressure measurements are related to fair weather, while low atmospheric pressure causes poor and unstable weather conditions. Lift is necessary to create atmospheric instability. It can be caused by rising air or low pressure. Updrafts, which is rising air, can be measured by testing wind speed and direction. Updrafts are often responsible for the more dramatic storm actions because they cause rapid instability in the atmosphere by pushing low pressure air upward.

    Barometer

    • Barometers, as the name implies, measure barometric pressure. Mercury and aneroid barometers are the most common barometers. Mercury barometers are tubes holding mercury that rises or falls depending on the air pressure. Aneroid barometers measure atmospheric pressure in aneroid or sylphon cells.

    Meteorological Balloon

    • Meteorological balloons can be used to measure atmospheric stability, specifically by measuring atmospheric conditions high in the air. Meteorological balloons can measure air pressure, humidity, wind speed and temperature, and usually consist of a lightweight rubber "balloon" filled with hydrogen or helium. They are released into the atmosphere and fly miles into the atmosphere to take and relay the measurements back to ground.

    Methods

    • Methods take measurements of certain qualities of the atmosphere to reach a cumulative assessment of the atmosphere's stability. The Pasquill-Gifford Method, for example, measures surface wind, surface temperature, solar radiation, cloud cover and cloud height. It is useful to take these measurements when there are no scientists in the vicinity and it is necessary to know the stability of the atmosphere. So, for instance, when there is high surface heat and low surface wind, unstable conditions are more likely to occur.

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