Here’s a fun one for Friday. Look closely at this photo taken by CTV News viewer Richard Tessier at about 1:30pm yesterday. At first glance, you might think a crane is punching a hole in the clouds above the dockyard in Esquimalt. “The cloud looks like a perfect circle,” he writes in his email.
In fact, this is weather phenomenon is known by a few different names: a fall streak hole, cloud hole, hole punch cloud, punch hole cloud or sky punch. Sometimes it’s also called a canal cloud. Whatever you call it, how this happens is “cool”. Ahem. A little weather geek humour…I digress…
I’ll call it a fall streak hole.
A fall streak hole sometimes appears in cirrocumulus or altocumulus clouds. This layer of cloud is made up of tiny water droplets that are below freezing, but not frozen. They’re called supercooled water droplets. If ice crystals finally form in this layer they will grow rapidly, in turn causing the supercooled droplets to shrink or even evaporate completely.
In this case it appears that this type of evaporation took place, as there isn’t any evidence of rain or snow falling from the middle of the hole. Google any of the above listed names of this weather phenomenon and you’ll see some amazing pictures of what that looks like.
Studies have shown that aircraft can trigger the development of a fall streak hole. Some suggest UFO’s are responsible. I can’t offer an opinion on that, but I’m happy to share the science behind it!
If you have a weather question or snap a photo of something weather related that you’d like me to explain, email me at islandweather@ctv.ca or as your question on our website, www.vancouverisland.ctvnews.ca/weather
Have a good weekend!
