Tag Archives: wind shear

Kelvin-Helmholtz Clouds Look Like Ocean Waves in the Sky

Peter Lobner

I recently saw the following spectacular photos of Kelvin-Helmholtz clouds that had occurred a few days earlier in Wyoming. The website EarthSky, which posted the first photo, reported, “Kelvin-Helmholtz clouds are named for Lord Kelvin and Hermann von Helmholtz, who studied the physics of the instability that leads to this type of cloud formation.” 

 Kelvin-Helmholtz clouds in Sheridan, Wyoming, 6 December 2022.
Source: Abbie Long, via EarthSky Community Photos: https://earthsky.org/earthsky-community-photos/entry/54020/
Kelvin-Helmholtz clouds in Wyoming, 9 December 2022
Source: Rachel Gordon / Facebook via BBC: https://www.bbc.com/news/world-us-canada-63912257

The Hydrometeorology Group website (https://hydrometeology-group1.weebly.com/kelvinndashhelmholtz-instability.html) reports, “Kelvin-Helmholtz clouds are the product of a strong wind shear. Wind shear refers to the rate of change of wind speed, or wind direction, over a set distance. The formation of Kelvin-Helmholtz clouds requires the presence of two vertical air layers of different densities that travel at different speeds. The upper layer must be the warmer and less dense of the two. Given a great enough wind shear, eddies will develop where the two air layers meet.”This type of process is illustrated in the following diagram.

Formation of Kelvin-Helmholtz clouds. 
Source: SKYbrary (https://www.skybrary.aero/articles/kelvin-helmholtz-waves)

You’ll find more photos and details on Kelvin-Helmholtz clouds in the following March 2022 EarthSky article, which notes that Kelvin-Helmholtz formations also can be observed at the interfaces of some cloud bands encircling Jupiter and Saturn: https://earthsky.org/earth/kelvin-helmholtz-clouds/

Kelvin-Helmholtz clouds pattern formed between two of Saturn’s cloud bands.
Source: Astronomy.com (https://astronomy.com/news/2004/10/turbulent-clouds-and-a-rock-steadied-ring

Could Kelvin-Helm clouds have been the inspiration for Vincent Van Gogh’s post-impressionistic masterpiece, The Starry Night, which he painted while recovering in an asylum in Saint Rémy (Provence) France in June 1889?

Source: MoMA, https://www.moma.org/collection/works/79802

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