How Clouds Form

Clouds may look like fluffy bunches of cotton floating way up in the air, but what are they really, and how clouds form?

Humidity – Think of a hot, sticky day, somewhere like a jungle where you’d feel moist and sweaty.  Compare that to a hot, dry day in the desert where your lips crack and your skin is dry and itchy.  What you can feel is the humidity, or amount of water vapor (gas) in the air.  In general, cool air can’t hold as much water vapor as hot air, so it normally feels drier and more comfortable.

Water Vapor and Condensation – Water vapor is an invisible gas.  If you look around you, you can’t see the air and the water vapor held in it.  But when water vapor loses heat energy and turns back into liquid water, which is called condensation, you can see it again!

Clouds – The clouds that you can see up in the sky are actually made of tiny droplets of liquid water (condensation) floating in the air.  Light passing through the drops bends in different directions, and the scattered light looks white to our eyes.  Normally, these drops of water float around and re-evaporate, while new ones form.  That’s why if you watch clouds carefully, you’ll see that they are always changing.

How Clouds Form – Hot air rises, and as it rises, it also cools down.  If that air had a lot of water vapor in it, there will be a point where, as it cools down, the air can no longer hold all of the moisture.  This is called the dew point.  Once air passes the dew point, some of the water condenses to those drops we mentioned, and we start to see clouds.  And if enough drops get together – RAIN!

Check out more facts about the weather!