Document text
Much more than hot air By MELISSA MARTIN Mail Tribune What's filled with the earth's lightest element, travels through sub-zero temperatures and flies higher than a fighter jet? It's a hydrogen-filled balloon that National Weather Service crews release twice daily, collecting upper-air data about temperature, humidity and wind. "The atmosphere is an ocean of air, always moving, always changing," said Roger Williams, meteorologist in charge of the National Weather Service office in Medford. "This information we gather twice a day, we use it daily no matter what forecast we're preparing." Mail Tribune / Jim Craven Larry Jacobs, a technician with the National Weather Service in Medford, releases a weather balloon on Friday. He and others on the Medford balloon squad were recently named the western region winners of the Isaac M. Cline award, which honors the work of "upper-air stations" in the United States. In 1999, the squad was named the top team out of 93 across the United States. The National Weather Service recently named the Medford balloon squad as the western region winner of the Isaac M. Cline award, which honors the work of "upper-air stations" in the United States. In 1999, the squad was named the top team out of 93 across the United States. National Weather Service crews in Medford have been launching balloons since 1939. The balloons are oblong and measure about 6 feet in height and 3 feet in diameter. "There's no other technology that will gather information at 100,000 feet as inexpensively as the balloon does," Williams said. The office spends about $270 daily releasing neoprene spheres carrying an expendable instrument called a radiosonde. The balloon drifts about 125 miles as it climbs nearly 19 miles up for 21/2 hours. Finally, as the pressure change expands the balloon, it explodes and an orange parachute cushions the radiosonde's fall back to Earth. Sometimes hunters, hikers or mushroom gatherers discover the radiosondes as far away as Chiloquin or high in the Cascade Mountains. The dimensions of the instrument, including protective padding, are similar to a sheet of paper, but 3 inches thick. There's a stamped envelope so the finder can mail the mysterious object to a weather service recycling center in Kansas City. "A few years ago, I sent the balloon up in the afternoon and before I left work that night, it fell on the freeway right in front of a motorist," said Chuck Glaser, data acquisition program manager. "He brought it back and the battery in the radiosonde was still hot." The radiosonde records temperature and humidity each second, beaming radio signals to an 8-foot antenna on the roof of the National Weather Service office near the Medford airport. Temperatures drop and pressure builds as the balloon gets higher. On a recent January day, it was minus 30 degrees Fahrenheit at 18,000 feet, said meteorologist Roger Gerig, veteran balloon team member. Medford's balloon data is sent to the National Center for Environmental Prediction in Camp Springs, Md., along with information collected by 92 other balloons launched across the United States at exactly 3 a.m. and 3 p.m. Greenwich Time. The data is fed into computer models to help create forecasts. "Data gathered by the balloons show lines of equal pressure, where the fronts are coming in and where the moisture is," Glaser said. The information is used for media, aviation and marine weather forecasts. And in Medford, balloon data helps calculate the ventilation index for air-quality advisories. The bowl-shaped Rogue Valley experiences inversions - cold foggy, winter days in which the air is warmer aloft than on the ground, Williams said. If there's no wind, everything produced on earth - smoke from chimneys and carbon monoxide from cars - hits a ceiling. "Smoke is about 104 to 110 degrees and will rise looking for a friendly environment," Williams explained. "It will go to the warm air, stop, and there's no mixing. But everything that's underneath, hangs there. It's like putting a lid on a jar." The balloon measures how tightly the lid is screwed on the jar. If the air is too stagnant, environmental officials issue a ban on wood burning that day. The temperatures measured by the balloons demonstrate the atmosphere's protection for people living on the warm surface of the earth instead of in the stratosphere's sub-zero temperatures. "The incoming solar radiation can't warm up that level," Williams said. "There aren't enough building blocks to hold out that temperature." Reach reporter Melissa Martin at 776-4497, or e-mail [email protected] Mail Tribune Home | Ottaway Newspapers, Inc. | Dow Jones & Co., Inc. | Privacy | Contact Us Copyright � 2001 Mail Tribune, Inc.