Many viewers couldn’t help but take a picture of a strange sight in the Massachusetts sky on Saturday. It is what’s commonly called a ‘hole punch’ cloud.
The image included here is from Salem, Massachusetts. The high puffy clouds you see are very likely composed of ice crystals and very small super-cooled liquid water droplets. Super-cooled simply refers to a case where liquid exists at temperatures well below freezing.
Assuming the atmosphere is reasonably stable, the ice and super-cooled droplets can coexist in close proximity. However, ‘hole punch’ clouds form when that’s no longer the case. When the atmosphere becomes agitated, some of the drops rapidly freeze into ice crystals. The ice crystals grow as more water droplets flow towards them.
That process results in the void, or clear circular area you see in the sky. In the center of that circle is often a wispy area, which is the concentration of newly formed ice crystals. Some say the wispy cloud that forms looks like it’s falling from the circle, hence the ‘Fallstreak Hole’ or ‘Hole Punch’ name.
Of course, you need a trigger to agitate the atmosphere and get this process underway. In many cases it’s caused by a plane flying through the clouds, and disturbing the coexistence of the ice and super-cooled.