Have you ever observed an airplane soaring through a clear blue sky? Sometimes it’s easy to track the path of an airplane because it leaves a white streak behind. However, after some time, the trail of the plane fades away and disappears.
Those white streaks that airplanes leave behind are actually man-made clouds. They are known as contrails, which is a shortened form of the term “condensation trail.”
Airplane engines produce exhaust, similar to car engines. As the hot exhaust gases escape from the plane, they come in contact with the air. At altitudes of 26,000 feet or higher, the air is extremely cold (sometimes below -40° F!).
The cold air causes the water vapor in the exhaust gases to condense. This means that the water vapor turns into small water droplets or freezes into tiny ice crystals before eventually evaporating. The condensed water vapor and mixture of ice crystals form the cloud-like trails visible in the sky.
If you have ever witnessed an air show, you may have seen airplanes creating messages in the sky that resemble clouds. Are these contrails? Not exactly…
Skywriters utilize small airplanes equipped with special smoke machines to fly in specific patterns and create visible written messages from the ground. The smoke machines usually consist of pressurized containers filled with oil. Upon the pilot’s command, the machines spray oil onto the hot exhaust system of the plane, where it quickly burns and generates dense white smoke clouds.
Pilots must learn how to fly specific patterns and operate the smoke machines carefully in order to create their unique messages in the sky. From advertisements to marriage proposals, the messages can serve practical, personal, or even humorous purposes.
Skywriting has a long history, dating back to before World War I, possibly as early as 1915. Nowadays, skywriters utilize satellite navigation to program messages before the flight, which increases accuracy.
Give It a Try
Ready to create your own contrails? Great! Grab the keys to your family’s airplane and take off into the sky! Wait, your family doesn’t have an airplane? Well, now that we think about it… even if they did, they probably wouldn’t allow you to fly it just yet! Don’t worry though, you can still have fun by trying out one or more of the following activities with a friend or family member:
Have you ever created homemade cards for your loved ones on their birthdays? There’s nothing quite like a sincere message written by hand in a card that you made yourself. However, paper has its limitations in terms of the impact your message can have. But what if you had the entire sky as your canvas? What would you write in the sky for a friend or family member if you had the opportunity? Ponder on it, and then share with that person what you would write if you could skywrite. You never know when you might just brighten someone’s day!
Is it overcast outside today? We hope so! Why? Because this activity requires some clouds. Go outside with some friends or family members, lay out a blanket, and comfortably gaze at the clouds as they move across the sky. What shapes do you see? Focus on a particular part of the sky and see what you can identify. Do your companions see the same things as you do? Compare your observations. How are they alike? How are they different? Have a great time cloudgazing and using your imagination to assign meaning to the random clouds!
If you’re up for a challenge, try this enjoyable experiment at home using just a few simple materials. Get a transparent plastic 2-liter bottle, matches (make sure to have an adult assist you with this experiment), and some warm water. Simply follow the instructions to create your very own Cloud in a Bottle!
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