All About Clouds

Nearly every day you can look up to the sky and see at least one cloud floating around. Clouds come in all shapes and sizes, and can be thin and wispy or dark and heavy with rain. But at their core, all clouds are made of the same basic molecule: water vapor!

How Clouds Form

During the water cycle, water is evaporated from the surface of the earth as water vapor and condenses into tiny water droplets in the sky that we see as clouds. However, the water vapor needs a non-gaseous surface to stick to when it condenses into droplets, a  process called heterogeneous nucleation.  During this process, miniscule particles in the air (often in the form of dust or soot) provide a surface that water vapor can condense on, allowing clouds to form. We refer to these particles as condensation nuclei.

Sometimes you can speed up the natural process of cloud formation by adding artificial condensation nuclei; this process is called cloud seeding. Why would you want to accelerate the formation of clouds? It’s a form of weather modification; something people do to either increase the amount of precipitation or suppress hail and fog. Cloud seeding in the United States is used in areas of drought and to prevent too much fog around airports.

Types of Clouds

This is an example of what cirrus clouds look like!

There are ten basic cloud types that can be separated into three categories: high clouds, mid clouds, and low clouds. The high clouds category is composed of cirrus, cirrostratus, and cirrocumulus clouds that form high in the sky. These clouds all have the appearance of being wispy like hair, and can often let the sun or moon shine through them. Cirrus clouds are detached and almost always made up of ice crystals. Cirrostratus clouds form a sheet over most of the visible sky. And cirrocumulus clouds are like a mixture of the other two: detached and sheet-like at the same time.

Mid clouds appear blue or grey, and take up the middle level of the sky. Altostratus clouds are sheets or layers of darker clouds that take up most or all of the sky. Altocumulus clouds have “rolls” or ridges and often occur in conjunction with other cloud types. Nimbostratus clouds are what we refer to as rain clouds. It forms from multiple layers of the altostratus cloud coming together. As precipitation continues, the nimbostratus cloud moves into the low level of clouds.

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The lowest level of clouds are those that appear closest to the Earth’s surface, and are often very dense. Cumulus clouds develop vertically in the form of rising mounds or towers that resemble the head of a cauliflower! Stratus clouds are dark and heavy, and if they’re dense enough they can produce drizzle or snow grains. Stratocumulus clouds are grey or white and form in patches that resemble honeycombs! Last but not least, we have the mighty thunderstorm cloud: the cumulonimbus. This cloud looks like a mountain with a smoother top and a dark base that produces precipitation. Cumulonimbus clouds can also produce tornadoes.

Cumulonimbus clouds look pretty fluffy!

Make Your Own Cloud in a Jar

In order to make your own cloud in a jar, we know we need warm water to cool, and some sort of condensation nuclei. It’s best to try this out with another person to help. Here’s what you’ll need for this activity:

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• A glass jar
  
• Hot water
  
• Ice cubes
  
• A few matches (the smoke will be our condensation nuclei)
  

First, pour some hot water into the jar, about ⅓ of the volume. Then, have one person light a match while the other prepares to quickly put the lid on. As soon as the match is lit, hold the flame inside the mouth of the jar over the water for a few seconds.

​Blow out the match, keeping some smoke on the inside of the jar. The second person will then quickly replace the jar’s lid and put a few ice cubes on top. Now you can watch as a cloud forms in your jar!


For further reference, here’s a YouTube video made by Dr. E showing how to make a cloud in a jar!

References:

“Ten Basic Cloud Types”  The National Weather Service, National Oceanic and Atmospheric Administration.  http://www.srh.noaa.gov/jetstream/clouds/cloudwise/types.html

Nyren-Erickson, Erin.  “How to Make a Cloud in a Jar”.  YouTube, uploaded on 9/26/2016.  https://www.youtube.com/watch?v=ODCjZQUxCGw  


Image credits:

Lee, Alix. “Cloud Sea Panorama”. Released into the public domain. Uploaded on 5/13/17 from publicdomainpictures.net

Carlson, Ronald. “Cloud Texture”. Released into the public domain. Uploaded on 5/13/17 from publicdomainpictures.net

Greyling, Lynn. “Layered Cumulus Cloud”. Released into the public domain. Uploaded on 5/13/17 from publicdomainpictures.net

Rabe, Foto. “Burning Matchstick Fire”. Released into the public domain. Uploaded on 5/13/17 from publicdomainpictures.net