We've learned that when the air is full of water vapor that is called humidity.
And we learned that the Dew Point is the temperature when water vapor turns into water droplets.
When the air close to the earth is very humid, and the temperature is very close to the dew point, it can turn into fog.
Fog is just like a big cloud full of water vapor and tiny water droplets.
If the temperature drops, then the water droplets may turn into rain.
If the temperature rises, then the water droplets will evaporate into the air.
(from: wikipedia - fog)
Kid Facts - Blast from the past: Quartz
