Canal cloudsWe’ve previously covered the neat atmospheric phenomenon of hole-p…
We’ve previously covered the neat atmospheric phenomenon of hole-punch clouds (see here: https://tmblr.co/Zyv2Js1k-Dtuu). Once water in the atmosphere gets cold enough to form ice crystals at the ambient pressure conditions, small perturbations can cause ice crystals to form rapidly and sink downwards as a flow from a single spot in a cloud. It looks like the cloud has had a “hole punched” in it as part of the cloud has just fallen towards the surface. These clouds are also called “fall-streak” clouds.
The open lines you see in these clouds are a similar phenomenon, just along a line rather than a point. Canal clouds are an open gap forming in clouds as ice crystals form and sink along a line rather than a point. Previous research suggests that the passage of an airliner is enough to trigger hole punch clouds – canal clouds could be the same thing from planes that wind up disturbing the air on a line if they enter the cloud at the elevation of instability.
Image credit: MODIS/NASA’s Terra Satellite