Norman, Oklahoma. Just around the corner from the National Weather Center in Norman, Oklahoma, a small cylinder-block building with antennas and a sphere on the roof marks the site of crucial weather data collection. Reinforced to withstand a gas explosion, it’s the base for Norman’s daily weather balloon launch. Yes, balloons — one of the oldest forecasting tools reliably capturing weather warnings today.
Every day at 0 Z and 12 Z (6 a.m. and 6 p.m. CST) over 700 locations worldwide release a weather balloon. “It’s a picture of the atmosphere around the world at a given hour,” says Forrest Mitchell, the observations program leader for the National Weather Service in Norman. A weather balloon is a helium-filled vehicle that lifts a radiosonde, an instrument that takes atmospheric measurements every second, to 100,000 feet above Earth’s surface.
While the process of launching a balloon hasn’t changed since 1938, the instrument technology keeps progressing. Through its antenna, the radiosonde sends the data it collects back to the National Weather Service headquarters in Silver Springs, Maryland — between six and 7,000 readings. Computers crunch the data into figures on wind speed and direction, temperature, humidity and atmospheric pressure. These combined measurements provide a baseline for weather models and forecasts for severe weather over the next 12 hours.
Weather balloon operators Forrest Mitchell and Daryl Williams have been launching balloons for almost three decades. “So we’re starting to get the hang of it,” Mitchell jokes. On a windy evening at the beginning of May, Mitchell and Williams explained the process of launching a balloon.
Photo at top: Solid surfaces will reflect the radiosonde’s transmitted energy and cause it to burn out. Operators place the instrument on a styrofoam block, which absorbs the energy, preflight. (Morgan Levey/ MEDILL)