Shaving Cream Cloud

This is ALWAYS one of the favorite experiments I do with groups of kids.  It will teach us principles of cloud physics that any grade level can understand, but it’s also fun to play with shaving cream and food coloring J

A word of caution: lay down some newspaper or paper towels.  Unless you (or your kids) do this carefully, it can get messy. When you’ve finished, I’ve found the easiest was to clean up is dump the contents of your jar into the toilet and flush immediately.  Everything else can go in the trash. 

What you need:

Clear vase/jar

Water

Shaving cream

Food coloring

What you do:

Fill the vase 2/3 with water to represent the atmosphere

Spray a thin layer of shaving cream to represent a cloud

Notice the bottom of the cloud is consistent across the whole vase. In nature this is called the LCL - lifted condensation level. Clouds basically form at a floor and can only build up from there. That “floor” is determined by the temperature and moisture content of the air at that moment, so the height level is different from day to day. 

The thin layer of shaving cream makes the experiment a little easier because it won’t take as long to saturate the cloud with your food coloring raindrops. The same principle is true in nature! The thicker, taller clouds can hold more rain, so when the rain does eventually fall, there is generally more of it compared to the thinner clouds. We call that stratiform rain because it’s usually more spread out across a wider area, but the rain is lighter. 

Back to the experiment: drop the food coloring into the shaving cream cloud. First just do a couple drops.  Notice how the drops stay in the cloud and don’t fall out. The cloud isn’t saturated yet. Then add several more drops until they start falling through the cloud like rain.  Now the cloud is saturated, or full, of raindrops. It can’t hold them in anymore, so they fall out just like the drops of food coloring are doing.