What does it mean if the realative humidity is 79%.?

Question

What does it mean if the realative humidity is 79%.?

Answer 1

It means that the air is holding only 79 percent of the water vapour for that temperature.

Answer 2

It means, in layman terms that a certain block of air "parcel" is 79% full of water.

Lets forget about air for a minute.  Take a dry sponge, lets say a sponge that is 3 inches cubed or 3 inches by 3 inches by 3 inches.

Now start pouring water on top and you will see that that sponge wil soak it up.

There comes a point however where that particular 3 inch cubed sponge will start leaking/dripping water - you could say that sponge (that 3 in cubic sponge is saturated with water and is at 100% humidity)

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There is no set or standard size to a "parcel of air".  You could maybe say 3 miles high by 3 miles wide by 3 miles horizontally.

It doesn't really matter - just look at air like a giant sponge.  It can only hold so much water just like a sponge.

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When they say that the realive humidity in your "region" whatever that is - is 79% - what they are saying is that....

the air around you is pretty darn moist and if it the humidity increased any more, you would be living in a cloud/fog - it would be raining/snowing, or thunderstorms, etc.

Clouds from - as you increase in altitude - the temp decreases by 4 1/2 degrees F per 1000 ft.  The cloud bases all appear the same as this is when the sponge starts to drip out the water.  As air gets colder - it can't hold as much water.  The sponge decreases with the same amount of water in it and as you get higher - clouds start to form.

If you had 100% humidity where you were currently at - you would be in a fog/cloud.  Fog=cloud.  Fog is a cloud at ground level at 100% humidity.