1Two things about air and water
Air secretly carries water — and there's a limit
You only need two ideas. Watch each one:
Air carries invisible water
Mixed into the air all around you is water you can't see. It's not droplets and it's not steam — it's water spread out so finely it's completely invisible. We call that invisible water vapor.
Warm air carries more than cool air
Air can only hold so much invisible water — and the limit changes with temperature. Warm air has lots of room. Cool air has very little. Same air, different limit.
2Roomy air vs crowded air
The same water, two very different rooms
Picture the air as a room for water. The temperature decides how big the room is:
The roomy carrier
Lots of space, so all the water spreads out and stays invisible. The air looks perfectly clear.
The crowded carrier
Cooling can bring water vapor to saturation. Some then condenses into tiny droplets we can see as fog. Air does not literally squeeze the water out.
3Your turn — fill the air with water
Pour invisible water in until the air can't hold it
Here the temperature stays the same. Slide to add more and more invisible water. Watch the air's water-room fill up — and see what happens when you pour in more than it can hold.
4Now run a whole morning
Two fields, the same warming morning
Two closed model fields begin equally cold and foggy. Field A contains 3.5 water units; field B contains 7.0. Warm both by the same amount, keeping their water amounts fixed. Does the same warming give the same result?
Guess before you drive the sun
After both fields reach the marked morning temperature, will both be clear, or will the wetter field still have fog?