Why do I see vapor rising from my solar heated pool at night/ in the morning when the relative humidity is 100% ?
Evaporation/ relative humidity
- Thread starter Rob36
- Start date
If it's evaporation, I thought evaporation doesn't happen when the relative humidity is 100% ?
Because it's heated water. Water temperature and air temperature always play into the calculation. I learnt it in skool.
Relative humidity is relative to the air temperature. The air above the pool is warmer than the air near the thermometer but has the same amount of water in it, so its relative humidity would be lower than 100%.
Thanks for your reply, so even if the relative humidity is 100%, as long as the pool is heated, and the air temperature is cool, there will still be evaporation?, even with 100% relative humidity, technically there's no place for the evaporated water to go, as I understand it from what I've read. I saw vapor rising from my pool when the weather chart Said 100% relative humidity. Seeing is believing. Thanks again for your response.
With the pool warmer than the air, it is transferring heat to the air immediately above the water. That drops the RH, so water then evaporates. But the air above that level is cooler and at the boundary the RH increases - causing condensation of the evaporated water, which is the mist/vapor you saw. Air currents likely drifted it over the decking/furniture/and surrounding area where it was deposited as dew. Or a thunderstorm, if your pool is really, really big.
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