Psychrometric formula

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psychrometric formula

(Also known as hygrometric formula.) The semi-empirical relation giving the vapor pressure in terms of the barometer and psychrometer readings.

For temperatures in degrees Celsius, this formula is
ams2001glos-Pe60
where T and Tw are the dry-bulb and wet-bulb temperatures, respectively; e is the vapor pressure; es(Tw) is the saturation vapor pressure at the wet-bulb temperature; and p is pressure. For temperatures below freezing, with the wet bulb covered with ice, 6.60 × 10-4 is replaced by, approximately, 5.82 X 10-4.

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