qThe easiest way to measure humidity is through use of a sling psychrometer - A pair of thermometers one of which has a wetted cotton wick attached to the bulb.
qThe two thermometers measure the wet and dry bulb temperature.
qSwinging the psychrometer causes air to circulate about the bulbs.
qWhen air is unsaturated, evaporation occurs from the wet bulb which cools the bulb.
qOnce evaporation occurs, the wet bulb temperature stabilizes allowing for comparison with the dry bulb temperature.
qThe wet bulb depression is found with a greater depression indicative of a dry atmosphere.
qCharts gauge the amount of atmospheric humidity.
qAspirated and hair hygrometers are alternatives.