Unusual “punch hole clouds” appear at dawn

An unusual “punch hole cloud” formation was seen over Spokane and North Idaho this morning, caused by ice crystals from jet exhaust falling downward through the sky, the National Weather Service said. The holes appeared in a fine layer of altocumulus clouds hovering around 20,000 feet in elevation. Jet aircraft traveling from northwest to southeast at around 35,000 feet left a trail of ice crystals from their exhaust, said forecaster Ron Miller. Those ice crystals drifted downward in the relatively stable air mass, reaching the altocumulus clouds, which were composed of water droplets. As the ice crystals passed through the clouds, the water droplets (the white clouds) adhered to the ice, causing the mass of fluffy white globes to take on a darker visual appearance. Miller said the elongated holes, or streaks, extended from about Coeur d’Alene to Lookout Pass. The last time such clouds were seen in the Inland Northwest was in 2010, he said. Visual-light satellite images from above confirmed that three to four of the streaky holes occurred this morning, Miller said.