On a warm day in January of last year, Martin Heinritzi peered from a window of his research plane, spotting Australia’s ...

Like a lot of people, I've been into clouds since I was a child. I loved to imagine them as animals in the sky. I loved getting lost in daydreams, staring at them out the windows during a boring ...

According to Space.com, these human-made clouds form between 32,000 and 42,000 feet. You may not see a contrail behind every plane that you see due to the environment that is always changing.

If you’ve ever looked up at the sky and watched a plane fly by, you’ve probably noticed a long white cloud streaming behind it and wondered what that line is.

Airplanes passing through this cloud layer often bring those ice crystals. Once introduced, the water droplets quickly freeze, grow, and start to fall, leaving a hole behind.

The sky formations are known as "cavum clouds" or "fallstreak holes." Here we explore unique facts about these "hole-punch clouds." Learn how passing airplanes shape their formation.

Contrail clouds from passing jet planes streak the sky over the Utah desert. Credit: Tonywestphoto via Getty Images Get the Popular Science daily newsletter💡 ...