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You may have notice that humidness ( the amount of water vapor in the air ) makes a remainder in how comfortable you feel outside . When the humidity is high-pitched in the summer we say it is " muggy . " When it is cool and humidity is high we may say that it feel " clammy . " Humidity can make a warm day feel warmer and a cool day find cold . you could observe the difference of opinion that humidity makes .
In this experimentation , you will define the relative humidity using moisture - light bulb and dry - bulb thermometers . Such a machine is called a psychrometer .
A vintage psychrometer. These devices have been used for more than 100 years to measure the moisture content, or relative humidity, in the air.
What you need:
What to do:
1 . economic consumption tapeline to secure the thermometer to the composition board rectangle about 5 in aside . verify the medulla stop of the thermometers hang below the border of the cardboard by at least 1 in and the numbered sides of the thermometer can be easily interpret .
2 . Set the thermometers in front of a small fan coiffe to a temperate speed for 5 arcminute and record the temperature reading . This is to avow that your thermometers are calibrated and show the same temperature under ascendancy conditions .
3 . Saturate several cotton plant balls with quick piddle and apply the rubber striation to get them around the bulb of one thermometer . Set the thermometers in front of the fan as before . After 5 minutes tape the “ wet electric-light bulb ” temperature reading and the “ dry bulb ” temperature reading .
4 . To determine proportional humidness deduct the lower “ wet lightbulb ” temperature from the higher “ dry lightbulb ” temperature to determine the difference and liken to the chart .
Results :
Even though the air temperature did not switch , you should have notice a lower temperature indication from the wet - electric-light bulb thermometer . This find because as the cotton balls were dry , some of the water evaporated ( change to water vapor . )
This alteration of state , from limpid body of water to water vapour , requires a bit of heat energy from the environ ambience . The same matter happens when ice thawing into liquid water . On the other script , a flyspeck bit of heating system is liberate when water system vaporisation condenses back into liquid figure or when water freezes to take form glass . This explains why you sense cold when you get out of a pool on a Laputan day , even though the airwave temperature is high , the water evaporating from your pelt is pulling the vaporisation heating system from your organic structure instead of the atmosphere !
