21 December 2017
You see those strange holes in the clouds across Indiana and Ohio? These are fallstreak holes or “hole punch” clouds, and they happen when aircraft fly through clouds of supercooled water. These clouds are well below 0° C, but the cloud droplets are still liquid (water will not always freeze into crystals of ice until the temperature reaches about -40° F/-40° C).
If a few ice crystals are introduced, then a rapid change will occur and the crystals will form. What happens next has been the subject of much debate in the past but a new paper in Science may have hit on the answer. A post on the Cloud Appreciation Society website explains it with a link the journal article. Yes, there is such a thing as the Cloud Appreciation Society, and of course, I’m a member!