Weather Instuments & Units
The Barometer is a instrument to measure pressure. It can measure the pressure of air, water, or mercury. The barometer is a great tool to forecast changes in weather. An Aneroid Barometer is the one we use that measures air pressure. This is measured in Inches normally.
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This You tube video shows all about the barometer in a Two minute time frame. It demonstrates how it's used.
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The Psychrometer is an instrument to measure the dew point, which then calculates to the Relative humidity. It can also can be refer ed to a wet- and dry scale thermometer or sling psychrometer. The amount of evaporation, and cooling of the thermometer on the wet scale side, depends on the humidity of the atmosphere. The drier the atmosphere the faster is the water will evaporate.
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Here is a video on the history of the Hygrometer (http://www.youtube.com/watch?v=ZdVhwJ9TM_0&feature=related)
A Raingauge is an instrument to gather the amount of liquid precipitation. Most rain gauge measure in millimeters. Now this instrument can not measure the amount of water for a hurricane, but it can measure a rainstorm amount. When using one, make sure it is not near any roofs or object blockers. That way you get the exact amount. Here is a video below on how to use a rain gauge.
More about Rain gauges
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