The Science Behind Helium Balloons

Balloons lighten our mood and add colour to any space. And for adventure seekers, a bunch of balloons means an opportunity to take off. Many have tried flying with the help of balloons, especially those filled with helium. Why helium? What’s the science behind it? Read on to know more…

Once upon a time, there lived an old man who turned his house into a makeshift airship, by tying thousands of helium balloons to it? He did so to fulfil a promise made to his late wife of moving to a cliff near ‘Paradise Falls’ in South America before the balloons deflate. Does the story ring a bell? Yes, it’s the plot of Disney’s 2009 film Up . But the idea is not entirely fiction. Many have tried flying with the help of balloons, especially those filled with helium. As recently as last month, a psychotherapist-cum-artist, Noemi Lakmaier, was lifted up by 20,000 balloons at Sydney Opera House. She was mid-air for nine hours to overcome her fear of flying. The past two decades have witnessed a rise in the cluster and lawn chair balloonists. Let’s see the science behind such airships…

What is a helium balloon?

Gas balloons filled with helium are called helium balloons. When you hold their strings, they ride along above your head and if you let go, they can be out of sight in no time. Helium balloons are used in birthday parties and celebrations, where they are mass-released into the air. Helium is lighter than air. While a litre of air weighs about 1.25 grams, a litre of helium weighs only 0.18 grams. Therefore, a balloon filled with helium would weigh less than the one filled with air. Helium balloons work by the law of buoyancy (or the Archimedes’ Principle) you learnt in middle school. The buoyant force from air pressure (which is equal to the weight of the air displaced by the balloon) acts on the balloon and pushes it upward. It keeps the balloon afloat, without pulling it down by gravitational force.

Why don’t they stay afloat longer?

Typically, the buoyancy lasts a day, as the helium atoms escape through small pores in the latex balloon. Whereas a balloon filled with air can retain its size much longer. In fact, hydrogen weighs even lesser than helium. But because of their combustibility, it is not preferred in gas balloons.

What are some milestones in ballooning?

The practice of using balloons, both gas and hot air, to fly is called ballooning. The first ever manned ballooning dates back to 1783, when French brothers Joseph-Michel Montgolfier and Jacques-Etienne Montgolfier built a hot air balloon and gave their first public demonstration on June 4 that year. There have been many milestones in the field, including a flight across the English Channel. As far as helium ones are concerned, key events include the one by Explorer II high-altitude balloon, piloted by U.S. Armymen in 1935, which reached a record height of 72,395 ft. In 1982, a truck driver from California, Larry Walters picked up 45 weather balloons and tethered them to his aluminum lawn chair. He rocketed to 16,000 feet. After shooting a few balloons, the balloonist landed on Long Beach. He popularised lawnchair ballooning. In 2001, Brit Mike Howard and American Steve Davis flew 18,300 feet over Albuquerque, New Mexico, using 1,400 helium toy balloons.

What are the other uses of helium balloons?

The Soviet Union used helium balloons to study the atmosphere of Venus. It dropped two helium balloons using the probes Vega 1 and 2 in 1985 into the planet’s atmosphere. The balloons provided data about wind and atmospheric conditions for 46 hours. Human rights activists and South African government use large helium balloons to send messages across to the people of North Korea.The balloons they float across the border carry news from the outside world, foreign currency and gifts such as personal hygiene supplies.

Why are helium balloons considered harmful?

When helium balloons are released, the helium atoms eventually get mixed into space, sending back chunks of latex to the ground, which are often mistaken for food by animals and birds. The remains either block the animal’s airways and choke them, or get lodged in their digestive tract causing a fatal illness. Scientists are also against wasting non-renewable helium in balloons. Inhaling helium can be harmful.

How different are hot air balloons from gas balloons?

In hot air balloons, an on-board burner heats up air and provides the required lift. Whereas, in gas balloons, helium (or hydrogen) is filled, to generate lift.

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