Humidity definitions and measurement devices

[Delta2]

I know there are three definitions of humidity. Absolute , relative and specific. Can you tell me if on a typical commercial device (such as the one i have in a clock i have) that measures humidity as percentage is it the relative humidity that it measures? Can the percentage become greater than 100%?

 

[davenn]

Can you tell me if on a typical commercial device (such as the one i have in a clock i have) that measures humidity as percentage is it the relative humidity that it measures?

When measured as a percentage, its a reference to RH - relative humidity its measuring the relative difference between absolute humidity ( actual water content) and the maximum water content that the air can have at a given temperature

Can the percentage become greater than 100%?

not that I have ever seen or heard of

... in non tropical climates, 100% would usually mean its raining. In tropical climates, I have often seen 95 - 100% and still not raining, but ohhhh gosh, the air is just so unbearable and "sticky"
Air temperature and pressure have a large bearing on this

It never ceases to amaze me how much moisture the air can hold as invisible vapour

Dave

 

[Chestermiller]

relative humidity its measuring the relative difference between absolute humidity ( actual water content) and the maximum water content that the air can have at a given temperature

More precisely, it's the ratio of the water vapor partial pressure in the air to the equilibrium vapor pressure of water at the air temperature.

Chet

 

[davenn]

LOL yup ... didn't want to go too deep