Sun dims, thermals fizzle

August 22, 2017 By Mike Collins

Pilots gathered in Montrose, Colorado, for a weeklong Soarfari, and a pair of Stemme motorgliders headed northeast from Montrose Regional Airport to view the partial eclipse in flight.

During the partial solar eclipse, a Stemme S-10 motorglider flies during the maximum 88 percent totality between Montrose and Rifle, Colorado. A number of Stemme motorglider owners had gathered in Montrose for a weeklong Soarfari. Photo by Mike Collins.
Wes Chumley, a Stemme demonstration pilot flying an S-12 motorglider, breaks away from a Stemme S-10 during the solar eclipse. It had reached 88 percent totality between Montrose and Rifle, Colorado, where the aircraft were flying. Photo by Mike Collins.
A Stemme S-10 motorglider flies beneath the partial eclipse between Montrose and Rifle, Colorado, where it reached 88 percent of totality. Stemme motorglider owners had gathered in Montrose for a Soarfari. Photo by Mike Collins.
Jerry Hain of Tucson, Arizona, and Lea Mattson of Boulder, Colorado, land a Stemme S-10 motorglider in Montrose, Colorado, after a flight to view the partial solar eclipse experienced in the area. They were in Montrose for a weeklong Stemme Soarfari. Photo by Mike Collins.
A Stemme S-10 motorglider flies between Montrose and Rifle, Colorado, during the partial solar eclipse--there, it reached 88 percent of totality. It was one of more than 10 Stemme motorgliders that had gathered in Montrose for a weeklong flying event. Photo by Mike Collins.
Lift eludes Wes Chumley, a Stemme demonstration pilot, flying an S-12 motorglider back to Montrose, Colorado, on a flight to view the partial solar eclipse. Photo by Mike Collins.

The objective was Rifle Garfield County Airport in Rifle, Colorado, where 90 percent totality was expected; Montrose would have only 85 percent coverage.

With a slightly delayed departure and a climb to 12,500 feet—Montrose is at 5,758 feet msl—they got almost halfway when maximum coverage was reached at about 11:41 a.m. Mountain time. By 11:30 a.m. the sky took on the darkened appearance of an overcast, but cloud coverage was sparse.

“I was surprised there wasn’t more difference in the amount of light available,” said Wes Chumley, a Stemme demonstration pilot flying an S-12. “The light just sort of changed color.” Soaring back toward Montrose, however, he found absolutely no thermals. Neither did other pilots up at the time. They concluded that the reduced solar heating delayed their formation. Indeed, people on the ground at the Montrose airport said they believed temperatures dropped as much as 20 degrees at the time of maximum solar coverage.

“It didn’t get nearly as dark as I thought it would,” said Lea Mattson of Boulder, Colorado, who viewed the eclipse from a Stemme S-10. “It was more amber colored. More than the color, I noticed the temperature difference. It felt noticeably cooler.”

“I thought it was going to get to more of a twilight, but it was like a late evening,” said Jerry Hain of Tucson, Arizona, another Stemme demonstration pilot flying with Mattson. “But the coloration was interesting.”

Both Hain and Mattson said that for the next solar eclipse, they will fly closer to totality.

Mike Collins

Technical Editor

Mike Collins, AOPA technical editor and director of business development, died at age 59 on February 25, 2021. He was an integral part of the AOPA Media team for nearly 30 years, and held many key editorial roles at AOPA Pilot, Flight Training, and AOPA Online. He was a gifted writer, editor, photographer, audio storyteller, and videographer, and was an instrument-rated pilot and drone pilot.

Go to Mike Collins's Profile

Sun dims, thermals fizzle

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