Can someone define to me what Realtive Humidity is?

Question

All I know is that it's the amount of water vapor in the air divided by the amount that would have to be present in the same air to form a cloud or condense on a surface. can some elaborate on it?

Answer 1

If the air were saturated, with all the water vapor it could possibly hold--it would be 100% relative humidity.  I actually heard this given in a weather report once--I think it was during a blizzard.

If the air had no water in it at all, just totally empty of water (maybe over the Sahara Desert or something), it would be 0% relative humidity.

The "relative" part means, compared to how much there would be if it were saturated.  50% means it contains half as much as it possibly could.  Some humidity feels good--but if you have too much, the air feels heavy and "muggy", your perspiration doesn't evaporate very well, and you feel cranky.