Image talk:Psychrometric chart simplified.png
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Some down to earth description how the chart is used:
A wet bulb temperature you measure by taking a small thermometer, covering the mercury or temperature sensitive portion of an electronic thermometer with wet cotton, tying the whole thermometer to the end of a string, then swinging it round and round above your head, whoosh whoosh, making sure the cotton does not fly off and stays well moist. Then read the temperature, swing it whoosh whoosh around some more so it cools some more, read it again until you get the lowest temperature you can. That is the wet bulb temperature. It is difficult to do it right, lots of care needed for accuracy. Looking at a dry bulb that is not covered in wet cotton, you get the dry bulb temperature, and from the two numbers you read the relative humidity off the chart, where you follow the dry bulb temperature up from the x axis, and the wet bulb from the 100% humidity line along the wet bulb line, and where the two lines (vertical dry bulb and southeast sloping wet bulb) meet is your current air conditions, and you read (interpolate, guesstimate) the relative humidity from the relative humidity lines shown on top and on the side. Sillybilly 22:58, 16 March 2007 (UTC)
