weather balloon

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weather balloon,

lighter-than-air craft without a propulsion system, lifted by inflation of one or more containers with a gas lighter than air or with heated air. During flight, altitude may be gained by discarding ballast (e.g.
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 used in the measurement and evaluation of mostly upper atmospheric conditions (see atmosphereatmosphere
[Gr.,=sphere of air], the mixture of gases surrounding a celestial body with sufficient gravity to maintain it. Although some details about the atmospheres of other planets and satellites are known, only the earth's atmosphere has been well studied, the science of
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). Information may be gathered during the vertical ascent of the balloon through the atmosphere or during its motions once it has reached a predetermined maximum altitude. Today, atmospheric information is most often gathered by height-finding radar, remote sensing by earth-orbiting or stationary satellites, and aircraft instruments, with weather balloons augmenting the data. Helium, which is less dense than air (see buoyancybuoyancy
, upward force exerted by a fluid on any body immersed in it. Buoyant force can be explained in terms of Archimedes' principle.
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), is usually used to inflate weather balloons. A pilot balloon is a small balloon (diameter c.1 m/39 in.) whose ascent is followed visually to obtain data for the computation of the speed and direction of winds at different altitudes. A smaller ceiling balloon is used to determine the altitude of cloud bases. A much larger, teardrop-shaped balloon is used to carry a radiosonderadiosonde
, group of instruments for simultaneous measurement and radio transmission of meteorological data, including temperature, pressure, and humidity of the atmosphere.
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 aloft. The balloon expands as it rises, usually reaching an altitude of at least 90,000 ft (27,400 m) before it bursts. A small parachute lowers the instruments to the ground. Teardrop-shaped balloons are also used for horizontal sounding of the atmosphere. Atmospheric pressure, temperature, and humidity information may be sent by radio from a balloon; monitoring of its movement provides information about winds at its flight level. Techniques also have been developed whereby many horizontal sounding balloons can be monitored by earth-orbiting satellitessatellite, artificial,
object constructed by humans and placed in orbit around the earth or other celestial body (see also space probe). The satellite is lifted from the earth's surface by a rocket and, once placed in orbit, maintains its motion without further rocket propulsion.
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 that relay information to earth-based stations. The tetroon is a tetrahedral balloon used for horizontal sounding. It was developed to withstand the extremely low pressures of high-altitude flight; the straight seals joining its four triangular faces are stronger than the curved seals of the more traditionally shaped balloons. Tetroons have been used extensively in tracing low-level atmospheric currents by following their movement with radar; they have thus increased the meteorologist's understanding of atmospheric turbulence, low-level vertical motions, and air pollution dispersion.
References in periodicals archive ?
Weather balloons are reliably manufactured to high standards, and greater than 90% burst between 13 and 9 mb.
A view of Aberystwyth from the weather balloon launched from a school playground
Its report concluded the incident had involved the crash of a high-altitude weather balloon being used in a top secret project to detect evidence of Soviet nuclear tests.
He wrote to RAF Valley saying: "Are our children being subjected, as some say in the village, to punishment by a gang of Hooray Henrys for daring to ask if they will fly over open fields instead of a children's nursery?" In another missive he warned: "Since you have refused to send independent observers to Parc Cefni I will be arranging for a weather balloon to be raised daily at the corner of our property.
TEEN'S AMAZING PHOTO: Two high school students captured this image of Earth using equipment carried aloft by a weather balloon.
Part 101 of the FAA regulations has rules for weather balloon flights and limits the weight to less than six pounds (or 12 pounds if it's towing two packages).
(3) "Weather Balloon Spurs Bomb Scare," The Boston Herald, August 3, 2002.
Book One (1599050102) includes The Presidential Ghost, Mystery Spots On Earth, and UFO Or Weather Balloon?; Book Two (1599050110) features Bob Lazar, The UFO Guy, The Mothman Mystery, and Mischievous Spirits; Book Three (1599050129) focuses on The Jersey Devil, Phantom Ships, and Living Dinosaurs?; Book Four (1599050137) reveals What Lurks Beneath The Waves?, Winchester Mystery House, and Skulls Of Doom; and Book Five (1599050145) has King Tut's Curse, Amazing Athletic Feats, and Monster Or Myth?.
PRISONERS had to be evacuated from a Scots prison after a fallen weather balloon sparked a bomb scare.
AG3 Mandy Fetterman launches a 100-gram weather balloon as part of her duties to gather and record weather information aboard USS Preble (DDG 88).
Weather satellite observations, the only truly global measurements, independently confirmed by weather balloon data, show little if any rise in mean temperature.