Most everyone at some point has looked up to the sky to admire the fluffy white clouds floating by, or have been threatened by dark, gloomy storm clouds preparing to soak the earth. How often, though, have you and your STEMists thought about clouds, how they are formed, and their purpose?
Clouds have several important functions. They provide rain and snow and help the earth’s atmosphere retain heat, similar to a blanket keeping you warm. When you look up to a clear starry night sky, you may find the temperature outside is cold, whereas if the night sky is filled with a blanket of clouds, the temperature may be warmer. On the other hand, clouds keep you cool by providing shade as they block out the hot sun.
How do clouds start?
Clouds are formed when warm air, or heat energy, rises then cools as it expands into the atmosphere. Water vapor in the air condenses on small solid particles like dust and sea salt, creating water droplets that form into clouds. And, it is the temperature of the atmosphere and the height at which the clouds are forming that will determine if the cloud you are looking at is composed of ice or water droplets.
Types of Clouds
STEMists should be able to identify the three main types of clouds—Stratus, Cumulus, and Cirrus.
- Stratus clouds are the lowest forming clouds and look like a crinkled flat sheet across the sky. Stratus clouds often mean an overcast day, especially near coastal and mountain areas. You can expect the air to be damp and a day of steady rain, or drizzles and mist. These clouds can hang overhead for several days before dissipating or moving on.
- Cumulus clouds are the fluffy clouds that look like puffs of cotton that sit on a flat base. They are the most common clouds and are some of the prettiest that form over land on bright sunny days. Cumulus clouds form close to the ground, about 3,000 feet, and are the ones that you often feel you can reach out and touch. Cumulus clouds grow upwards but beware of cumulus clouds that grow tall, especially if they appear before midday. These clouds can bring sudden rains, hail, and thunderstorms. Shorter cumulus clouds indicate fair weather.
- Cirrus clouds are some of the highest clouds in our atmosphere and look like wispy streaks of feathers. These clouds are made of ice particles because they are so high in the sky. Cirrus clouds scattered across a clear blue sky indicate fair weather.
Cloud Activities for STEMists
Cloud in a Jar
Items you will need for this groovy experiment are glass jar with lid (or small plate or bowl); ice; dark colored paper; aerosol air freshener or hairspray; and a flashlight is optional. Fill the bottom of the clean glass jar with hot water (130-145 degrees) approximately 1 inch deep. Swirl water in jar to warm the sides of the glass. Place ice cubes in the lid (acting as a bowl) and place it on top of the jar. Watch the condensation and notice the absence of a cloud. Then, spray a small amount of your air freshener into the jar and quickly replace the ice-filled lid. Now hold up the dark colored paper to the glass and look for wisps of cloud to start swirling inside. You may also want to shine a flashlight inside the jar to see the cloud better. Finally, remove the lid and let the cloud rise out of the jar so that you and your STEMists can touch it.
Check out this video for an alternative way to do this experiment:
Edible Cumulus Sky
Use a Mason-type jar for this activity—small for individual serving sizes or a large jar for sharing. Ingredients needed are whipped topping, like Cool Whip, blue-colored gelatin, ice and water. In a bowl, mix one small package of gelatin with one cup of boiling water. Add one cup of ice cubes, and stir until the gelatin thickens to a consistency between liquid and firm. Then begin to layer whipped topping and the gelatin. Use a spoon to plop and push the topping along the side of the jar. Continue to layer the ingredients until you have various shapes and sizes of white puffiness among a clear blue gelatin sky. Let the gelatin completely set in the refrigerator for another 30 minutes or so. Be sure to let your STEMists admire the shapes and remind them about the characteristics of the cumulus clouds. Bon Appétit!
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