Horseshoe cloud

A horseshoe cloud is a relatively uncommon meteorological phenomenon^[1] which manifests as a cloud in the shape of a horseshoe or inverted letter "U".^[1][2]

They occur when a horseshoe vortex deforms a cumulus cloud.^[2] The clouds are relatively short-lived^[2] and is the last stage before one dissipates.^[3] Horseshoe vortex clouds are a form of "fair-weather" funnel cloud and are similar to the shear funnel type of funnel cloud.^{[citation needed]}

A March 2018 instance was explained by the United States National Weather Service:^[4][5]

As the updraft pushes flattish cumulus clouds up & a horizontal vortex develops from differential updraft speeds... As the vortex climbs, it's caught in the faster horizontal winds aloft, & the middle part of the vortex catches the faster speeds with the ends being slower.

These clouds do not occur often because all the needed conditions rarely occur together.^[3]

References

Wikimedia Commons has media related to Horseshoe vortices at Cumulus clouds.

1. ^ ^{a b} "Horseshoe Vortex Cloud (February 07)". Cloud Appreciation Society. January 31, 2007. Retrieved March 12, 2018.
2. ^ ^{a b c} "An incredibly rare 'horseshoe cloud' was spotted in Nevada and it kept the meme-makers busy". Independent.ie. March 12, 2018. Retrieved March 12, 2018.
3. ^ ^{a b} Baer, Stephanie K. (March 10, 2018). "People On Twitter Are Freaking Out Over This Rare Type Of Cloud". BuzzFeed News. Retrieved February 2, 2023.
4. ^ @NWSElko (March 9, 2018). "As the updraft pushes flattish cumulus clouds up & a horizontal vortex develops from differential updraft speeds..." (Tweet) – via Twitter.
5. ^ @NWSElko (March 9, 2018). "As the vortex climbs, it's caught in the faster horizontal winds aloft,& the middle part of the vortex catches the faster speeds with the ends being slower" (Tweet) – via Twitter.