Issue link: https://www.epageflip.net/i/18261
When is it safe for balloons to fly? By MARY SPICER McClatchy-Tribune When it comes to predicting the impact a meteorological event will have on hot air balloon festivals, the opera- tive phrase is "it ain't over until it's over." In other words, no one really knows for sure whether hot air balloons are going to fly until they start pop- ping into the sky. Gener- ally speaking, balloons have a tendency not to fly when the wind is moving faster than 11 to 12 mph. However, if the overall wind speed is considerably lower but it's gusty, they aren't going to take off. That's because it's dangerous, according to Ted Watts Sr. "You just never know when the gusts are going to come, so you won't see bal- loons in the air," he said. By the same token, if winds are a bit over the 11- to 12-mph threshold but con- sistent, an experienced balloonist might decide to go ahead if suitable cover — often in the form of a tree line or build- ings — can be found to provide for take- off. Another general guideline calls for no flying if a thunderstorm is taking place within a 50-mile radius — 100 miles if the thunder-thumpies are especially fierce. That doesn't have much to do with the possibility of a lightning strike; it's because of the way thunder clouds are built. "You probably have seen bright, Red Bluff Daily News warm, sunny days when you have high, puffy clouds and then all of a sudden the clouds get dark and the wind picks up," Watts said. A thunderstorm forms when moisture gathers into the puf fy cumulus clouds and builds. An updraft gets start- ed; as the cloud builds, it gains intensity and strength. "Need- less to say, the air that's being drafted up has come from some- where -- typically the sur- face," Watts said. Once the storm gets to its mature stage, wind gusts can travel up and down the funnel. On the downward trip, when it hits the surface of the Earth, it spreads out. "If you've got a thunderstorm active within 50 miles, that could be sending wind currents along the surface that could be devastating for a balloon," Watts said. Just one of those microbursts could cause a 3-knot wind speed to jump to 20 knots in the blink of an eye. Rain falling from the sky will also bring a launch to screeching halt, but it's not just the danger caused by the weather itself. Moisture is the ultimate enemy of the hot air balloon envelope, which will degrade quickly if folded up and put away before it's completely dry. Three. Two. One ... If a window of opportunity opens, however, all bets are off. Even on the warmest, sunniest day, pilots may opt to keep their balloons grounded because of a phenomenon known as thermals. Friday, October 22, 2010 Page 7 "That's a function of the air heating and rising, which is of course what makes balloons fly," Watts said. "The reason we fly two hours before sunset is because we have to give the Earth a chance to cool down and that thermal activity to stop. If you fly too early on a warm day, you can have thermal activity that actually dis- rupts the flight of the balloon." All pilots control is the altitude, he said. "We heat the balloon, it goes up. We cool it, it comes down. That's all we con- trol. We don't have any steering capabili- ty whatsoever." The balloon can be sucked up by ther- mal activity, even though the air in the envelope hasn't been heated to its normal flying temperature. And if it's not heated to the proper temperature when it reaches the top of the thermal, it's going to come back down very quickly. Given that phenomenon, he said, "you can't afford to be in a hot air balloon in the middle of the day. It's just not feasi- ble." Pilots often get requests from people having a mid-day event — a picnic, for example — who want to include a teth- ered hot air balloon in the festivities. "Everybody talks about tethering like it's very benign," Watts said. "I would much rather fly a hot-air balloon in free flight than to tether it. It's not natural to have a balloon tied to the ground. It's sup- posed to be flying — so it's very danger- ous." The final decision about when to fly — or tether — always rests with the indi- vidual pilot. "If I'm in a rally and somebody calls a flight, if I don't feel comfortable flying in those conditions, then I have the respon- sibility to stay on the ground," Watts said. If there's any opportunity to fly what- soever, though, the pilots will get their balloons into the air. "Sometimes the organizers will say, 'Nah. The conditions are so squirrely, we're not going to call the task,' " Watts said. "We're not going to put the pressure on anybody to fly, but we'll open the field for pilots' discretion. That means we're not going to compete, but if you feel comfortable flying in these conditions, you're welcome to make that call."