Buehner: Weather balloons are more common than you think

There has been a lot of news about balloons lately. The Chinese recently sent a giant remote-controlled surveillance balloon with a huge payload across North America that they said was a weather balloon. It was shot down off the Carolina coast. Since then, the North American Aerospace Defense Command (NORAD) fine-tuned its radar surveillance system and began picking up much smaller balloons. Among those were real weather balloons.

Weather balloons are launched twice each day from about 900 locations around the world, providing a vertical snapshot of Earth’s atmosphere from the surface to well above where jets fly. They are simultaneously launched at midnight and noon Greenwich Mean Time (GMT) or 4 a.m. and 4 p.m. Pacific Standard Time (PST). Local launch locations include Quillayute on the north Washington coast, Spokane, Salem, Ore., and Port Hardy, BC – all among the more than 100 launch sites across North America.

The balloons carry an instrument package called a radiosonde upward through the atmosphere. The radiosonde instrument package collects information on temperature, humidity, pressure, and wind direction, and speed at various heights as the balloon rises.

The battery-powered radiosonde instrument package attached below the balloon collects and transmits data back to the launch site as it rises. Ground sensors at the launch point also follow the balloon as it moves with the wind aloft to measure wind direction and speed as the balloon ascends.

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The balloons themselves are made of latex and are inflated with either helium or hydrogen, measuring about 6 feet wide before release. As they rise, the balloon expands as air pressure decreases, often to about 20 feet in diameter before it bursts, usually between 40,000 and 80,000 feet. Clearly, weather balloons are far smaller than what the Chinese recently deployed.

Once the balloon bursts, a parachute on the instrument package deploys, and the radiosonde slowly falls back to the ground. If found, they can be reused by mailing it back using the attached mailing bag to a rehabilitation center in Kansas City, saving tax dollars. About one in five radiosondes are reused.

Weather balloons have been used to gather a vertical profile of the Earth’s atmosphere since the 1930s. The data is one of the key initial weather data resources for meteorological computer models of how the atmosphere from the surface to well above where jets fly will behave in the future.

These meteorological models are what meteorologists use to help predict the weather, including short-fused weather warnings like tornados and flash floods, as well as longer-term significant weather events like wind storms, hurricanes, and winter storms.

Over the years, with ever-enhancing computer power and resolution, these computer models have continued to improve, providing meteorologists with more accurate weather prediction information. Yet, near-century-old weather balloon technology still plays a key role in today’s weather observation and prediction process around the world. If you ever find a radiosonde, be sure to mail it back so it can be reused again.

Ted Buehner is KIRO Newsradio’s meteorlogist