Have you ever tried to explain to your kiddos how clouds and rain work, but you just can’t show them exactly how it works because the clouds are so high up in the sky? Well, here’s a fun and simple way to show them in a visual manner that is not only easy to understand, but exciting and easy to do! And most likely, you probably already have all the “ingredients” necessary right at home!

Let’s briefly talk about clouds and rain for a second before we get into the experiment.

What causes clouds?

Clouds are formed in the atmosphere when invisible water vapor condenses and become visible vapor or sometimes even ice crystals. These super small water droplets or ice crystals grab onto dust particles that are floating through the air, and they begin to group together. Depending on whether the vapor becomes ice crystals or super tiny droplets of water and their level in the atmosphere, the resulting cloud could appear drastically different from others.

Remember those little particles I mentioned? They are called aerosols. When the water vapor particles and the aerosol particles begin bumping into each other in the atmosphere, some of the water vapor will take a hold on the particles, resulting in something called condensation. As more and more of the water vapor grab onto the particles, they get larger. This begins to form the clouds. Super high and wispy cirrus clouds are made up of those tiny ice crystals, because the air is much much cooler at that height of the atmosphere. In order for these tiny droplets to become ice crystals, temperatures must be colder than approximately -20 degrees Farenheit, or around -30 degrees Celsius. If they are warmer, they remain tiny little water droplets. On the other hand, a low, dark cumulus cloud is made up of thousands upon thousands of tiny little water vapor droplets. There are many other factors that play into how clouds are formed, such as surface heating, convergence, frontal boundaries, topography, and even turbulence, but we won’t get into that today. Each different factor creates a different type of cloud. In fact, there are 10 basic cloud types:

• Cirrus
• Cirrostratus
• Cirrocumulus
• Altocumulus
• Altostratus
• Stratocumulus
• Nimbus
• Cumulonimbus
• Nimbostratus
• Stratus
• Cumulus

Credit: UCAR – Center for Science Education

What Causes Rain?

Now that we know the basics of how clouds are formed, let’s move on to rain. Precipitation can take on many forms, rain, snow, sleet, and hail, but most commonly we see rain here in the Pacific Northwest. Precipitation begins to take shape when the water vapor droplets we talked about above continue to grab onto those aerosol particles, until they become too large and heavy. At that point, they begin to fall through the cloud. Updraft air plays a vital role in helping create a cloud. Before they became too heavy, the updraft of air within the cloud and the atmosphere was strong enough to keep them from falling, but once they have gained enough weight, the updraft can no longer support them. Once they become heavy enough to leave the cloud, they begin their descent into the atmosphere below. Providing the precipitation, whether it be liquid water vapor or ice particles, does not evaporate back into the atmosphere, it will fall to the ground as rain, or other forms of precipitation depending on the conditions. When the precipitation does not reach the ground and evaporates back  in the atmosphere, it is what is called “Virga”.

The above image shows Virga, precipitation that is not reaching the ground, but is clearly visible before evaporating back into the atmosphere.
This was taken by me in Bothell, WA in spring 2016.

Here is another example of Virga, taken by me from Mukilteo, WA, summer 2016.

Now, one final question to answer. Why is it cloudy, but there isn’t any rain? That’s because there is either not enough water vapor forming and grabbing onto aerosols to form precipitation, OR the motion creating the cloud through updraft is not strong enough to support falling precipitation. So, just because you see clouds, it doesn’t mean it’s going to rain. The warmer the air mass is, precipitation will likely occur in much smaller, localized shower clouds, unless it is tropically rooted and there is a very large amount of water vapor available. Large amounts of tropically rooted water vapor is what our atmospheric river events are typically caused by. If the air mass is much cooler, precipitation is likely to occur in low pressure areas with large cloud zones; this commonly occurs along the boundary lines in between warm fronts and cold fronts.

Finally, it’s time for the fun part! Here’s what you need to grab to visualize clouds and rain!

“Ingredients”

• Quart Sized Mason Jar (smaller is ok too, I used a half pint because that’s all I had handy, but the bigger jars show the experiment a little better)
• White Shaving Cream
• Water
• Food Coloring – Color doesn’t matter, whatever color you want your rain to be!

Next, fill up your mason jar with water to about a 1/2 inch above the rim; this is your atmosphere! Then, take your shaving cream and put a small layer of cream completely across the top in the remaining half inch of space; this is your cloud! Once that’s completed, grab your food coloring and put about 10 or so drops directly onto the shaving cream; this is the rain! Now, we wait!

The food coloring “rain” will begin to work it’s way through the shaving cream “cloud”. This is essentially like when the water vapor begins grabbing onto the aerosols, becoming larger and larger until it is too heavy and begins to fall through the cloud. Eventually, your food coloring “rain” will get to the bottom of the shaving cream “cloud” and enter into the water “atmosphere”.

Look! It’s begun to rain food coloring! The food coloring became too heavy and made it’s way through the shaving cream “cloud”.

Here’s a fun close up look at the food coloring as it distributes itself through the water “atmosphere”.

The completed experiment! Now you can dump it out and start over, if you wish!
Pretty neat, huh?

You can explain this process to your kiddos in whatever manner they will understand best. This cloud be just talking about the weight of the water vapor and how it moves through the cloud, or you can explain to them the more technical details like I did above. You know the level of your child best, so this is where you come in to help explain it in a way that they can understand it. The visual definitely helps. It’s a fun, rainy day experiment to help highlight WHY it’s raining outside!

Here’s a few more images of rain, some Virga and some actually falling all the way to the ground, from spring 2016. It’s pretty amazing to live in the world we live in!

Please feel free to let me know what you thought of this experiment. I’d also love to hear what your kiddos think too! Leave me a comment here on the blog, or feel free to pop over to the facebook page to chat about it as well, at Little Bear Creek Weather!

(Images in this blog post, save for the cloud diagram courtesy of UCAR – Center for Science Education, were taken by me for my photography business, JB Hawkins Photography)