A strange cloud formation has left residents in Canada perplexed, after showing up in the sky several times this month.

Experts say the stunning clouds that look like a brushstroke are known as hole-punch clouds or fallstreak holes, and are caused by a rare - but rather ordinary - atmospheric occurrence.

These unfamiliar clouds form when temperatures are below freezing, but water droplets in the clouds have yet to freeze due to a lack of ice particles. 

When ice particles form quickly, it causes a domino effect as the water droplets connect with the crystals, which get heavier and then start to fall all of a sudden - leaving a large hole in the cloud.

The wispy clouds that form in the center of the hole are the water particles falling. 

Passing airplanes are thought to be the reason behind the formation of these clouds, since a drop in pressure caused by their wings or propeller tips cools the air quickly. 

Rainbows are sometimes seen with fallstreak clouds, thanks to light refracting off the water droplets.  

Â