balloons get their lift from hot air.
Balloons are often mistaken for UFOs. Weather
balloons at high altitudes are visible over a wide area and
may catch the light of a setting sun and appear as brilliant
dots in the darkening sky. Hot air, sport balloons, as well
as blimps may also be misidentified.
The first balloon flight was made on June 5,
1783 in France. The balloon, using hot air for lift, was constructed
by Joseph and Elienne Montgolfier. It climbed to 5,906 feet
and traveled nearly a mile. A few months later on November 21st,
of that year, Pilatre de Rozier and marquis d'Arlandes made
the first manned flight, also in a Montgolfier balloon.
Balloons are large bags filled with a gas that
is less dense, or lighter, than the air on the outside of the
bag. The less dense gas rises, the same way a bubble of air
does in water, carrying the bag with it.
Balloons come in several designs. The typical
round bag is used in sport and weather balloons. Dirigible designs
are long and sausage shaped. Dirigibles are divided into airships
with rigid frames, called zeppelins, and ones with no frame,
called blimps. Unlike sport balloons most dirigibles have motors
that allow the ship to sail where the pilot wishes, rather than
just being guided by the wind.
The gas inside the bag is usually either normal
air that has been heated (the temperature makes it less dense),
hydrogen, or helium. Hot air is used in most smaller sport balloons,
but is unsuitable for larger airships where it cools too quickly.
Instead helium or hydrogen gas is used.
Helium and hydrogen are two gases which are lighter
than air even at the same temperature as the air. Today helium
is almost universally used for non-hot air balloons because
of the explosive nature of hydrogen. Helium wasn't discovered
until 1895 and could be difficult to get even after it became
commercially available in 1918. Hydrogen is cheap (it can be
readily made by splitting water apart) and provides more lift.
This led to a disaster in 1937 when the zeppelin Hindenburg
caught fire in Lakehurst, New Jersey killing more than seventy
Today, of the dirigible design, only helium blimps
are operated. The famous Goodyear Blimp is used for advertising
around the world. Interestingly enough despite it's disc shape,
when seen from a distance, at least one study indicates that
it does not spawn surge of UFO reports when it is visiting an
weather ballon can rise to a height of 30 miles.
Lee Krystek 2007. All Rights Reserved.