How Do Sky Lanterns Work?


Many people don’t know how a sky lantern works. They simply light the fuel cell wait a few minutes and then release their lantern into the air. But the physics behind the entire process is quite interesting.

The very basics of it is that a sky lantern uses the heat generated by its candle to make it rise when the atmosphere around it is cooler. Flying lanterns are intriguing and never fail to astonish viewers. They have a a magical and mystic appearance as many observers wonder how they stay in the air, or what makes them float upwards and stay there for so long before gently descending back to Earth.

Sky lanterns can be seen quite frequently in the recent years. They are often seen at celebrations such as parties or anniversaries. Very few people can claim that they are not mesmerised or filled with enchantment at the sight of a bunch of paper lanterns being released simultaneously. When the sky is lit up by a lanterns at night or even in the daytime, you can see the physics in action. The average sky lantern stays in the air for around 15 to 20 minutes. This is quite  an astonishing amount of time for something is made from a candle and paper.

The physics of a sky lantern taking to the air is similar to that of a hot air balloon.  It uses hot air within the balloon to make it rise when the air around the outside of the balloon is cooler. The difference between a balloon and lantern is that the balloon has a pilot and basket attached.  A lantern has a candle or fuel cell which heats the air and this hot air fills the sky lantern. The consequence of this is that the lantern rises in the air.

This happens because the hot air inside the lantern is lighter than the cool air surrounding it. The body of the lantern gets hotter which is created by the heat from the fuel cell within the lantern. This fuel cell is lit before the lantern is launched. Approximately two minutes after lighting the lantern, the body will have enough hot air to rise up into the sky. As it floats up, the fuel cell continues to create hot air which fills the lantern and keeps it going.

When the fuel cell runs out, the lantern gradually runs out of heat and then it will slowly float back down to earth. There is no danger to the environment any surroundings at this point because the fuel cell has all been used up and is cool by the time it reaches the ground. Also, the lanterns are made from biodegradable materials and so there is no damage done to the environment in this sense either. The natural materials will simply degrade over time.

What also helps is process is that the materials used are lanterns of very light. They’re often made from materials such as rice paper, bamboo strips and a lightweight fuel cell. If the materials were too heavy, the Lantern would not get off the ground.


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