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National Weather Service Portland-Gray Maine

Upper-Air Program Virtual Tour
National Weather Service Forecast Office
Gray, Maine


Introduction Equipment Inflation Baseline Launch RRS Conclusion


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The next step of the virtual tour demonstrates how the National Weather Service prepares and launches an atmospheric sounding, beginning with the supplies needed for the launch.

Upper air supplies

Upper air supplies from left to right: Mark IIA radiosonde, balloon, twine, parachute, and train regulator.

Each flight utilizes a weather balloon or sounding balloon which is a large specially made latex balloon which is designed to carry the instrument aloft in upwards of 90,000 -100,000 feet! Prior to launch the balloon is roughly 6 feet wide, and when the balloon reaches its termination level, the balloon can be larger than a 2-car garage. This is because as the balloon ascends through the atmosphere, pressure decreases, thus, allowing the balloon to grow larger and larger the higher the balloon ascends.

Standard National Weather Service Weather Balloon Pre-inflations

Standard National Weather Service Weather Balloon Pre-inflation

 

Next we have the instrument (radiosonde) which measures the pressure, temperature, and humidity. The wind speed and wind direction are also measured by either a radio direction finding antenna or using the satellite based Global Positioning System (GPS). WFO Reno just recently went through the Radiosonde Replacement System upgrade and uses GPS based radiosondes.

Mark 11A Radiosonde with GPS Receiver

Mark IIA Radiosonde with GPS Receiver

 

The sounding train also includes a biodegradable parachute that deploys as the radiosonde returns to Earth after bursting at termination. Without it, the returning radiosonde could pose a danger to people or property since it weighs roughly one pound. The radiosonde will typically land well over 100 miles from the launching station.

Upper-Air Supplies - Twine, Train Regulator, and a Parachute

Upper-Air Supplies – Twine, Train Regulator, and a Parachute

 

During launches where high winds are present, a special radiosonde train regulator is used to help aid the observer with the launch. As the weather balloon ascends through the atmosphere, the radiosonde train regulator unwinds and slowly increases the train length to the desired length for the sounding, which is typical 80 120 feet.

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Gray Weather Forecast Office
P.O. Box 1208
Gray, ME 04039
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Page last modified: March 17th, 2009
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