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HUMIDITY. To understand water vapor in the atmosphere, you need to understand saturation . Saturation = filled to capacity There are several measures of humidity in the atmosphere:. Absolute Humidity. : The absolute amount of water in the air. Weight of Water Vapor in Air.
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HUMIDITY • To understand water vapor in the atmosphere, you need to understand saturation. • Saturation = filled to capacity • There are several measures of humidity in the atmosphere: Absolute Humidity : The absolute amount of water in the air Weight of Water Vapor in Air Absolute Humidity = Weight of Unit Volume of Air
HUMIDITY Specific Humidity : The amount of water in a unit MASS of Air Mass of Water Vapor in Air Specific Humidity = Mass of Air Specific Humidity is useful because the humidity is constant even as the Volume of the Air in question changes (due to Pressure).
HUMIDITY : The ratio of the air’s actual water content to its potential water vapor content at a given temperature. Relative Humidity Weight of Water Vapor in Air Relative Humidity = Weight of Potential Water Vapor in Air at Saturation • Basically, relative humidity tells you how saturated the air is with water.
HUMIDITY • Dewpoint Temperature: The temperature the air would have to be cooled to saturate the air (causes water to condense)
HUMIDITY • A psychrometer is used to measure relative humidity. • The dry bulb measures the air temperature • The wet bulb gives a measure of how unsaturated the air is—the evaporation of water from the wet bulb lowers the temperature reading (and the evaporation depends on the saturation of the air)