We've learned now that the water vapor that makes up clouds can come from evaporation or sublimation.
And we've learned that the opposite of evaporation is called condensation.
The opposite of sublimation is called deposition. That is when water vapor as a gas turns into a solid.
Usually water vapor would turn to liquid first, then freeze to be a solid.
But sometimes if it is really super cold out, the water vapor gas will turn right to a solid and freeze.
You can see this sometimes as frost, or even the snowflakes forming in clouds in the sky.
(from: wikipedia - deposition (phase transition))
Kid Facts - Blast from the past: Igneous Rocks
