|MadSci Network: Earth Sciences|
A barometer is a device used to measure the pressure of the atmosphere at a location (essentially we are weighing the air column above the barometer). A barograph is a chart that provides a continuous pressure trace a location over time. The important thing with air pressure is the trend in the pressure. Generally speaking, falling pressure means that bad weather is on the way while rising pressure means that fair weather is on the way. In addition, rapid changes in pressure are typically associated with windy conditions since these rapid changes are associated with large differences in pressure over an area. The larger (smaller) the difference in air pressure over an area, the stronger (weaker) the wind. If you notice that the pressure indicated by your barometer is falling quickly, you might be in for windy conditions and rain (snow or ice if it's cold). If the barometer is falling slowly, the winds probably won't be very strong and you might just have cloudy skies rather than rain or snow. Conversely, if the pressure is rising rapidly, you may experience windy conditions and quickly clearing skies (after it has been raining or cloudy). If the pressure is rising slowly, the winds probably won't be as strong and it may take a while for skies to clear, if they do at all.
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