Cool atmospheric phenomenon: fallstreak hole

This is one of the freakiest atmospheric happenings I have ever seen: a fallstreak hole from Victoria, Aus.

It is believed that the introduction of large numbers of tiny ice crystals into the cloud layer sets off this domino effect of evaporation which creates the hole. The ice crystals can be formed by passing aircraft which often have a large reduction in pressure behind the wing- or propeller-tips. This cools the air very quickly, and can produce a ribbon of ice crystals trailing in the aircraft’s wake. These ice crystals find themselves surrounded by droplets, grow quickly by the Bergeron process, causing the droplets to evaporate and creating a hole with brush-like streaks of ice crystals below it.

More photos of this particular hole can be found here.

• science