Striped linear cloud over Norfolk, England (Kelvin-Helmgoltz cloud)

Trailspotter

Senior Member.
I've spotted this unusual cloud this morning (August 29, 2015) from the car on the trip to the Norfolk Broads and observed it for about twenty minutes from 11:15 to 11:35 BST (10:15 - 10:35 UTC) until it was obscured by lower clouds. The cloud comprised regularly spaced transverse stripes:
K-H_cloud_1.jpg
K-H_cloud_3.jpg
K-H_cloud_6.jpg

The cloud was oriented along the wind direction (SW), coinciding with a general direction of our road (A11) and was moving northeast a bit faster than the car.

Interestingly, the cloud appears on the Terra satellite image taken at about 10:38 UTC, just a few minutes after my last photo:
85ff3b0aeec45ac24f9a37a4def72ad4._.jpg
From this image, the cloud's length was about 20 miles. Also, by the time, its distal end was already over the North Sea, some 35 miles away from our location at the time of the last photo. Using Google Earth, I've estimated the cloud's altitude being about 30,000 ft (9 km).

The cloud's wavy appearance suggests it may have resulted from the Kelvin-Helmholtz instability.
 

Trailspotter

Senior Member.
Here is another flickr photo taken closer to the coast, in which the cloud looks like a typical Kelvin-Helmholtz cloud:
 
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Trailspotter

Senior Member.
Aren't K-H clouds usually caused by vertical wind shear? I can't recall ever seeing one horizontally oriented before.
I think that this K-H cloud also was cased by vertical wind shear. It just was observed at an unusual angle. My and Norwich photos were more from the end, whereas the last one, from the Hickling Broad, was photographed more from a side, making cloud billows in the thicker end more apparent:
Norfolk K-H cloud.jpg
 

Spectrar Ghost

Senior Member.
I think that this K-H cloud also was cased by vertical wind shear. It just was observed at an unusual angle. My and Norwich photos were more from the end, whereas the last one, from the Hickling Broad, was photographed more from a side, making cloud billows in the thicker end more apparent:
Norfolk K-H cloud.jpg

I'm having a hard time with the perspective. It does appear that your second photo shows the same K-H cresting, but a bit disguised by (lower?) small clouds.
 

Trailspotter

Senior Member.
I'm having a hard time with the perspective. It does appear that your second photo shows the same K-H cresting, but a bit disguised by (lower?) small clouds.
I took a few zoomed photos through the side window with my iPhone that show the K-H cresting more clearly. Unfortunately, they all were spoiled by reflection, as I did not pull the glass down :oops:
K-H_cloud_2.jpg
 
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