Shaving cream rain clouds activity : Fizzics Education

Shaving cream rain clouds

Shaving cream rain clouds

Follow FizzicsEd 150 Science Experiments:

You will need:

Shaving cream

A plastic cup filled with water

A straw

Blue food colouring

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Shaving cream, a plastic cup filled with water, a pink straw and some blue food colouring
1 Adding shaving cream to the cup of water

Add shaving cream to the cup of water. Fill it up over the brim!

2 Using the straw to collect come blue food colouring

Use the straw to collect some of the blue food colouring. Place the end of the straw into the food colouring and then put your finger on top of the straw. As long as you keep your finger on the end of the straw, you should now be able to lift up the straw without the food colouring falling out.

This works due to air pressure pushing the food colouring up into the straw. An example of this can be seen in the upside-down water cup experiment!

3 Adding food colouring to the shaving cream

Carefully add drops of blue food colouring on top of the shaving cream

4 Blue food colouring moving from the shaving cream into the water

The food colouring will slowly move through the shaving cream until it reaches the water layer. At that point you’ll see the food colouring begin to stream out into the water.

5 Blue food colour pouring out of the shaving cream 'cloud'

As the food colouring is denser than the water, the food colouring drops to the bottom of the cup. A simple rain model!

Why Does This Happen?

Food colouring is denser than the shaving cream and the water. As such, the food colouring drops to the bottom of the cup, acting like rain!

Rain is a form of precipitation, whereby water vapour in a cloud condenses to form large enough drops to then fall out of the sky. Precipitation can take many forms: rain, drizzle,  hail, snow and sleet.  It all has to do with relative humidity, which means how much water there is in the air compared to the temperature. Warmer air can hold more water vapour than colder air.

  • If the temperature rises and the amount of water in the air is the same, the relative humidity has fallen.
  • If the temperature falls and the amount of water in the air is the same, the relative humidity has risen.

If the temperature of the air falls past the temperature needed for water to condense, the water in the air will form liquid droplets which will the fall as rain. We call the temperature that water vapour condenses the dew point. If it is cold enough (below freezing at ground level), these water droplets will rapidly freeze and form snow which can reach the ground if this temperature is below freezing at ground level.

Rain is a major part of the water cycle, where evaporating water from water bodies and the forms clouds which eventually forms rain to begin the process over again.

Variable to test

More on variables here

  • Try different food colours
  • If you place shaving cream on another liquid such as canola oil or glycerine, does the experiment work?
  • Can you use a different foam on top of the water such as pea foam or soap foam?

Learn more!

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