I noticed this morning that it was raining, and the air relative humidity was 62%, the air temperature in the kitchen was 14deg C. I thought it odd that if it was raining, the air RH should have been 100%, so assuming that as it was raining outside I should check RH and air temperature outside, which I did, air temp 11deg C, RH 68% so how come if it’s raining the RH isn’t 100%?
bob(from black rock) said:
Because rain and RH aren’t the same thing.
I noticed this morning that it was raining, and the air relative humidity was 62%, the air temperature in the kitchen was 14deg C. I thought it odd that if it was raining, the air RH should have been 100%, so assuming that as it was raining outside I should check RH and air temperature outside, which I did, air temp 11deg C, RH 68% so how come if it’s raining the RH isn’t 100%?
>>>Because rain and RH aren’t the same thing.
OK, so what is observable when the RH reaches 100%?
bob(from black rock) said:
>>>Because rain and RH aren’t the same thing.OK, so what is observable when the RH reaches 100%?
It doesn’t have to be raining though it my well be.
What is observable, well if the temperature is warm, breathing will be difficult and clothes will be too wet to wear.
Condensation forms when the air hits dew point, or the relative humidity is 100%. This usually happens when the air cools down and approaches saturation from above, as it were.
When it is raining, there is transfer of water from the rain to the air, but the driving force becomes smaller and smaller as saturation is approached, so it is never actually acheived. To get saturation coming from below you need agitation and extended surface areas to counteract the decreasing driving force.
Another factor might be that the rain itself is at a lower temperature than the air, so saturation will not be reached. Not too sure of that one.
Thats my take on it anyway, FWIW.
>>>Another factor might be that the rain itself is at a lower temperature than the air, so saturation will not be reached. Not too sure of that one.
morrie, that sounds reasonable to me, ta. Not sure why that has never occurred to me until today.