A seven-layer lenticular cloud formed around the summit of Mount Washington on Monday afternoon, a rare occurrence for weather observers on the mountain, Mount Washington Observatory officials said.
Lenticular clouds — officially known as Altocumulus Standing Lenticular clouds and often resembling flying saucers — are formed when an “optimal flow” of fast moving, and roughly perpendicular wind is forced over a mountain, according to Charlie Peachey, a weather observer on the Mount Washington summit.
Around 2:30 p.m. Monday, winds on the summit of the mountain in New Hampshire were between 65 and 85 miles per hour — only slightly higher than the average 50 to 60 mile per hour winds — when Peachey said he took a picture of the lenticular cloud.
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The clouds are not more common in a particular season, Peachey said, or affected by temperature. The main cause of the clouds is a “really strong perpendicular flow over a mountain range,” he said.
Peachey said lenticular clouds with two to three layers happen once or twice a week at Mount Washington, but he had never seen a seven-layer cloud before.
“I was blown away when I was looking at the cloud,” Peachey said. “After observation, I went inside to grab my camera and take pictures as soon as I could.”
Ava Berger can be reached at ava.berger@globe.com. Follow her @Ava_Berger_.