SAN FRANCISCO (KRON) – An unusual cloud formation has Bay Area residents puzzled Friday afternoon.
Several viewers reached out to KRON4 to ask what it was.
The phenomenon was seen mainly on the Peninsula in cities like San Bruno, San Mateo, and Burlingame.
But residents in the East Bay also tell KRON4 they spotted it in the sky.
The National Weather Service says the formation is known as a “fallstreak hole” or “hole punch cloud.”
The clouds form when there are water droplets that are much colder than freezing but have yet to freeze, according to the NWS.
These “supercooled” water droplets need a “reason” to freeze, which usually comes in the form of ice crystals, the NWS explains.
Planes passing through the cloud layer can bring these ice crystals, which is most likely what happened to make this cloud form in the Bay Area.