Fog: Inside a Cloud

Have you ever wondered what a cloud looks like from the inside?  If you've ever been in thick fog, you know.  Fog is a cloud at ground level.  It can form on clear nights when there is a lot of moisture in the air.   A cloudless sky allows heat to escape up into space.  Then the air near the ground cools enough for the moisture in the air to condense into a cloud.  Sometimes winds blow warm moist air over a cold surface such as water or ice, which causes the moisture to condense into fog.  When cool air moves over a warm lake or pond, moisture from the water's surface may evaporate and condense in the cool air.  This results in what is called steam fog.   You guessed it!  It looks like steam rising from the lake.



Make a Cloud

Try this experiment with a grownup to make a cloud in a bottle.  Get an empty two-liter plastic soda bottle and a match.  Put about an inch of water into the bottle, have a grownup light the match, hold it inside the bottle for a few seconds, then drop it inside.  Quickly put the cap on and shake the bottle to fill the air inside with moisture.   Give the bottle a squeeze.  The increased air pressure will warm the air inside.  Then release the bottle and allow the lower air pressure in the bottle to cool the air inside.  As the air cools, the water vapor inside the bottle should quickly condense on the smoke particles, forming a little cloud.  It really works!

Rise Up

Clouds form when moisture rises, cools, and changes to water or ice.  But what makes the moisture rise into the sky?  It can happen three ways: 1. Sunshine:  the heat of the sun can cause the air to rise, taking water vapor with it high into the sky. 2. A Front: a cold front will bring cold air under warm air, forcing it to rise; a warm front will force warm moist air up over the cold air. 3. Mountains: When winds blow against mountains, the moist air is forced upward.

Weather Ideas for elementary students:

1. Draw the different cloud types and explain what kind of weather might come from them.  (You might want to glue some cotton balls to your drawings!)
2. Cumulus clouds look like cotton balls and cirrus clouds look like strands of angel hair.  But what else do they remind you of?  What about stratus, nimbostratus, and cumulonimbus?  Share your ideas with your parents or teacher.
3. Choose a cloud type, huddle with other students, and then act it out.  Have the other students guess the cloud type.

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