CLEVELAND -- If you've looked at the sky above Cleveland Thursday, you may have noticed an unusual number of jet contrails streaking across the sky.

Newsnet5.com has been receiving dozens of e-mails from people who have noticed this strange sight.

Officials at Hopkins International Airport said that the contrails are more visible because of the atmospheric conditions, including clear skies, the temperature and stable air.

Also, northeast Ohioans live under the world's busiest air corridor, so there is plenty of air activity on the average day.

Power of 5 meteorologist Mark Johnson said the contrails are actually man-made cirrus clouds created by hot jet exhaust.

When the hot exhaust hits the cold atmosphere, condensation occurs, creating the trails. Johnson said if the atmosphere is humid, those trails can stay visible in the sky for several hours.