Is it a bird? A plane? A UFO? Weather balloons are sometime mistaken for unidentified fling objects, but they are actually floating weather stations in miniature; a collection of scientific instruments with the job of measuring temperature, humidity and atmospheric pressure.
* Parts of a Weather Balloon *
Although the measurement gear is high-tech, the equipment is held aloft by a very low-tech device, a large, extra tough balloon that is able to withstand high altitudes. In addition to devices for measuring climate, the equipment must also have a radio transmitter for remotely conveying the measurements.
The latex balloon is attached to a nylon rope, which is secured to the instruments, devices collectively known as a radiosonde. Specialized radiosondes are sometimes constructed to measure other types of atmospheric data, such as ozone and carbon dioxide levels. Tracking the weather balloon also provides data on wind direction and speed.
* How High Can a Weather Balloon Go? *
Weather balloons can withstand a lot of abuse, and can reach altitudes of about 40 kilometers. That’s high. For comparison, Mt. Everest is a little less than nine kilometers tall. The amount of hydrogen or helium gas used to fill the balloon determines how quickly will rise. As the balloon ascends, the atmosphere thins, allowing the balloon to expand until it disintegrates. Weather balloons are typically inflated to about 6 feet in diameter and expand to 20 feet before breaking apart.
* What Happens When the Balloon Pops? *
The miniature weather station continues to collect data until the balloon pops. When this happens, the instruments are often lost. Weather balloons sometimes do have GPS devices for tracking and recovery, and parachute is attached between the radiosonde to slow descent of the equipment, so that it can, in some cases, be salvaged.
* How Important Are Weather Balloons? *
Weather balloons provide vital data on weather patterns around the globe. The NOAA’s (National Oceanic and Atmospheric Administration) National Weather Service website reports that two times a day, at 12 and 24 Greenwich Mean Time (GMT), every day of the year, weather balloons are simultaneously released from about 900 locations worldwide.
You may wonder why, in an age of radar and satellites, weather balloons are needed at all. Even with all of today’s technology, weather balloons are the most accurate way of measuring conditions within the troposphere; the lowest major layer of the atmosphere, which extends from the Earth’s surface to the base of the stratosphere (1016 km up).
To learn more about how weather is measured and predicted, see the National Weather Service website. The site also provides information on international weather conditions.