Looks like flying jellyfish to us. Any cloud experts out there. Give us a clue!
From Belinda Goody, Weather Enthusiast
In all my wanderings, I have not seen this formation however, this looks similar to what we in the weather community call”VIRGA” or “vertically inclined trails of rain showers that do seemingly not touch the ground.”
Virga is an indication of strong surface winds, which are indicated in the photo.
Given the type of cloud generating this trail; fair weather cumulus – so no rain showers to speak of – hence the blue sky.
I suspect then this is colder, more dense water vapor “falling down” from the warmer, lighter clouds above.
“Mare’s tails”are generally cirrus clouds which are much higher (above cumulus) and made of ice crystals.
Cirrus make for chilly evenings and colorful sunsets.
That’s my best guess!