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DPT & Relative Humidity Charts. Handy Dandy Earth Science Reference Tables Page 747. 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 =.
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DPT & Relative Humidity Charts Handy Dandy Earth Science Reference Tables Page 747
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 • 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)
Dewpoint Temperature: The temperature the air would have to be cooled to saturate the air (causes water to condense
The “Dry Bulb” • Don’t let it fool you. It is just a thermometer. • It measures the air temperature. • Duh! 20°C
The “Wet Bulb” • Has a little wet booty tied to the bottom. • Gets cool when water evaporates. 12°C Wet Booty
14°C 20°C 12°C 8°C A Dry Day… • A lot of moisture will evaporate. • The wet bulb will be a lot cooler than the dry bulb. 20°C Difference between wet bulb & dry bulb is 12 °C.
A Humid Day… • A little bit of moisture will evaporate. • The wet bulb will not be much cooler than the dry bulb. 20°C 14°C Difference between wet bulb & dry bulb is 6 °C.
Page 747 & 750 of your Handy Dandy Earth Science Reference Tables • Warning #1: Be sure to READ the correct chart: DPT or RH • Warning #2: Dew Point Temperature IS NOT “Difference between wet bulb and dry bulb”. • Warning #3: The wet bulb temp IS NOT the DPT.
20°C 14°C 20-14=6
18°C 16°C 18-16=2
Put it all together 20°C 8°C 20-8=12 Relative Humidity = 11%
14°C 10°C 14-10=4 Relative Humidity = 60%
The Dew Point Chart works the same way 14°C 10°C 14-10=4 Dew Point = 6°C
Try These. 58% 17 °C 86% 4 °C 57% 4 °C 91% 16 °C 100% 14 °C 45% -9 °C
More Difficult. 82% 18 °C 45.5% -.5 °C 100% 17 °C 20% -17 °C 69% 3.5 °C 15 °C 21 °C 52% 11 °C(50 °F)