Materials and Equipment
The balloon itself produces the lift, and is usually made of a highly flexible latex material, though Chloroprene may also be used. The unit that performs the actual measurements and radio transmissions hangs at the lower end of the string, and is called a radiosonde. Specialized radiosondes are used for measuring particular parameters, such as determining the ozone concentration.
The balloon is usually filled with hydrogen due to lower cost, though helium can also be used. The ascent rate can be controlled by the amount of gas with which the balloon is filled. Weather balloons may reach altitudes of 40 km (25 miles) or more, limited by diminishing pressures causing the balloon to expand to such a degree (typically by a 100:1 factor) that it disintegrates. In this instance the instrument package is usually lost. Above that altitude sounding rockets are used, and for even higher altitudes satellites are used.
Major manufacturers of balloons are Zhuzhou Research & Design Institute, Chemchina Rubber Corp (Brand: Hwoyee), Totex and Cosmoprene of Japan and Pawan Rubber Products (Pawan Exports, Brand: PAWAN) of India,
Weather balloons are sometimes cited as the cause of UFO sightings, and are also used for cluster ballooning.
Read more about this topic: Weather Balloon
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