Now, for the virtual tour portion of how the National Weather Service prepares and launches an atmospheric sounding. First we begin by gathering our supplies for the launch.

Storage Room

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! On the surface 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-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 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, Chemlight, Train Regulator, and a Parachute

On the 12z ( 3am or 4am depending on season) a non-hazardous chemlight is attached to the sounding train to help aid in visibility. This is particularly helpful for aircraft.

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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