Winter contrails highlight Vermont skies

Dec. 15, 2021  |  By Emmett Gartner | Correspondent 

Contrails over Camel's Hump captured by Andrea McMahan in Duxbury.

Vermonters peering skyward early last week might have noticed a series of winding, curling clouds scrawled across a crisp blue background.  

The formations, known as contrails, are a product of F-35 training maneuvers and a special combination of atmospheric conditions that freeze their fluffy trails into place. As picturesque as the contrails were, Marcus Tracy, acting deputy of the State Public Affairs Office for the Vermont National Guard, notes that the maneuvers that produced them were nothing out of the ordinary.

“The 158th fighter wing has been conducting their training missions, but nothing outside our normal training operations for the last year,” Tracy said.“The vapor trails are produced from multiple different types of jet engine aircraft, from civilian to military aviation, when certain atmospheric conditions are present.”

Those certain atmospheric conditions, according to the U.S. National Weather Service in Burlington, were present last Tuesday.

“The types of contrails pictured are formed by the combination of the very cold temperatures at high altitudes and the water vapor and particles contained in aircraft exhaust,” a weather service spokesperson said. “As the added moisture and particulates mix with the cold air, condensation occurs on the particulates, which then freezes into ice particles, providing the atmosphere is at the proper temperature.”

How long the contrails linger is a measure of ambient temperature, humidity, and winds. All three combined on Tuesday to freeze the contrails in place for Vermonters across the region, from the Champlain Islands in the northwest to Camel’s Hump State Park further south over Duxbury.

Contrails overhead in Duxbury recently. Photo by Gordon Miller

Andrea McMahan lives just below Camel's Hump in Duxbury. She captured images of the swirling contrails overhead against a bright blue sky and shared on Facebook last week. 

“It was so strange. The sky was beautiful. By the time [the jets] got there it was still morning and the [contrails] were drifting east. They were spreading out, but it was enough to see the solar output drop” from her rooftop solar panels, McMahan said.

Some 40 miles away, Rob Swanson, a photojournalist for the Islander Newspaper in the Champlain Islands, was out walking his dogs on Tuesday when he noticed the contrails hanging above him.

“I didn’t have any of my real cameras with me, so I just started banging off pictures with my iPhone,” Swanson said.

For Swanson, formations like Tuesday’s were of special interest because of his fascination with Vermont’s skies.

“I shoot everything that moves in Grand Isle County. I shoot any aircraft, because we’re in between Burlington International and Plattsburgh. Any critters, any scenics, and any interesting clouds. We're a big sky country up here so we get a lot of interesting clouds,” Swanson said.

Swanson added, “It’s a phenomenon that doesn’t happen every time they fly. Just another cool thing in the sky, along with the moon, the sun, rainbows, and all of the different aircrafts.”

Swanson's photos are online in posts titled, "Only in the Islands," on The Islander newspaper's social media accounts, most often on Facebook.

Contrails fill the sky over the Champlain Islands in this shot by South Hero photojournalist Rob Swanson. Photo courtesy The Islander newspaper