GEO E111 Lecture Notes - Lecture 14: Wet-Bulb Temperature, Mixing Ratio, Hygrometer
Document Summary
Humidity is the condition of atmosphere with reference to its water content. It"s measured with hygrometer or psychrometer which consists of wet and dry bulb thermometers kept in stevenson screen. Dry bulb thermometer is a thermometer covered with muslin bag immersed in water while dry bulb thermometer has no muslin. When air is dry there is a lot of evaporation from the muslin. Evaporation cools the bulb of thermometer resulting in a low temperature reading. When humidity is high there is little evaporation from the muslin. The wet bulb thermometer is cooled at a slower rate and both thermometers show almost the same temperature reading. The difference in readings between the two thermometers is used to determine relative humidity. When the 2 readings are the same, relative humidity is 100% i. e. the air is saturated. If the difference is small, humidity is high. If the difference is big, humidity is very low.
