At what humidity does it start to rain?

Question

As far as I understand it is perfectly valid for air to have 100% humidity. At that point, all water can still exist in form of vapor, non-condensed. **Does it immediately start to rain if humidity is >100%?** If so, why do we have slight rain and heavy rain if any 0.1% above 100% drops out immediately? That should always be only a small amount of rain and rainstorms could not be explained. If not, what is the limit of humidity if not 100% and why can it exceed 100%? --- I have tried to understand the [Wikipedia article](https://en.wikipedia.org/wiki/Humidity) but I'm stuck in various places: > Water vapor is the gaseous state of water and is invisible *Invisible* to me would mean that clouds are excluded from humidity. > Absolute humidity is the total mass of water vapor present in a given volume of air. That again makes me think a cloud must be included. > The humidity is affected by winds and by rainfall. Rainfall certainly decreases humidity, but it is not stated at what percentage it starts to rain.

Answer 1

The humidity within clouds is essentially 100%, that is why they are clouds, essentially fog is GROUND CLOUDS. They can be thick clouds, more likely to have rain drops, because they form due to growing in size due to collisions, and evaporation, condensations to make droplets bigger, then they get so big they fall out of the cloud as rain. Or if it is cold enough as snow. Or wispy fair weather clouds, where air currents, and overall humidity in the region does not allow small droplets to grow big enough to fall.