A horseshoe cloud in 2016

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.

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. 1 2 "Horseshoe Vortex Cloud (February 07)". Cloud Appreciation Society. January 31, 2007. Retrieved March 12, 2018.
  2. 1 2 3 "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. 1 2 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.


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