Generally, a weather balloon goes up to an altitude of around 15 miles before bursting. This is almost thrice the height of Mount Everest.
Predicting weather conditions in not very easy. In the past, most natural calamities were predicted, or rather detected, barely a few hours before they hit. However, this situation has changed recently, with the advent of weather balloons.
With their help, we can now predict the atmospheric conditions a few days in advance, and be prepared to face it by taking precautionary measures. This has helped minimize the losses to both, life and property.
In the United States alone, there are around 92 stations from where these weather balloons are sent into the upper atmosphere. This is done twice a day. Across the world, there are around 900 weather stations. In accordance to international agreements, the readings of the atmospheric conditions are shared between various nations.
These balloons can be tracked by radar, radio direction finding or navigation systems like GPS. Though, this is mostly not done owing to the budget constrictions. Instead, many centers tag a prepaid postage envelope along with the apparatus, so that the finder can simply mail the device to the mailing address.
Frenchman Jean-Pierre Blanchard is the pioneer of balloon flight. In 1785, he flew across the English Channel from Paris. He was accompanied on this flight by John Jeffris, an American physician with a liking for weather observation. In 1896, Léon Teisserenc de Bort, another Frenchman, pioneered the first unmanned balloon flight in Trappes, France.
He was a meteorologist. For the following two years, up to 1898, he studied the atmospheric constitution through these unmanned balloons, that would climb up to 11 km (6.8 miles).
The material used in the production of these balloons is such that it can sustain varied temperatures and pressure changes. This has resulted in them scaling higher altitudes. They can now reach up to a height of 40 km (25 miles) before bursting.
The height at which the balloon bursts is not determined by the radius to which the balloon inflates, but by its weight. Higher the weight of the balloon, the more resistant it is to the variations in temperature and pressure, and more is the altitude to which it can climb.
The balloon is equipped with various instruments for recording and transmitting data. To lift this balloon, hydrogen or helium gas is used which are cheaper, and can be easily extracted from water. So, it was preferred in earlier weather balloons. But hydrogen gas is also highly inflammable, which is why helium is used in weather balloons.
This balloon is equipped with a parachute. After reaching higher levels in atmosphere, in its near-space voyage, the balloon expands and bursts. The parachute mounted on this balloon then opens and slows down its descent.
The balloon then reaches the Earth's surface at a speed of 9.8 m/s, instead of hurtling down with an acceleration of 9.8 m/s2 and causing huge damage to anything or anyone that comes in contact with a projectile that is in such a rapid descent.
What Does a Weather Balloon Do?
A weather balloon measures various weather conditions at varying altitude levels. It has various instruments that perform actual measurements. Radiosonde is a collection of all these instruments. A radiosonde consists of a 'thermistor' and 'hygristor' along with an 'aneroid barometer'. A thermistor is a ceramic-covered metal that acts as a thermometer.
A hygristor is a small slide with a coating of lithium chloride, which acts like a humidity sensor, while an aneroid barometer is a metal canister that measures air pressure. The radiosonde starts measuring various parameters, and simultaneously transmits data over the radio to the station soon after lift-off.
Hence, there is no need to retrieve the device for data readings after the balloon bursts. The balloon can land miles away from the site of initial lift-off.
Transosondes are those weather balloons that are mounted with various devices. These can stay at higher altitudes for a longer span of time. They were first used on an experimental basis in 1858. They were used to detect radioactive debris in the atmosphere from an atomic fallout.
A weather balloon measures atmospheric conditions at higher levels. This is helpful in predicting the weather conditions at ground level a few days in advance. This is very important to predict any natural disaster that may be lurking around the corner.
This balloon can be used by people with interests in aviatronics. It is also used to monitor pollution and its damages. It is useful for research purposes, along with photography and videography.
NASA has conducted some near space experiments with the help of weather balloons. These are cheap to use when compared to high altitude rockets or aircraft.
However, when the atmospheric conditions higher altitudes―which a weather balloon cannot reach―are to be observed and recorded, then sounding rockets are used. If there is a need to go to further heights, altitude satellites are used.