You may have gotten up and looked out the window Wednesday morning to spot these odd, wavy clouds at sunrise. As with most types of unique clouds, they too have an interesting story.
These are known as fluctus clouds, or more scientifically referred to as Kelvin-Helmholtz clouds.
They can look like breaking waves, or as one WDBJ7 viewer called them, "dolphins swimming through the sky."
HOW ARE THEY CREATED?
They are named after the Kelvin-Helmholtz instability that create beautiful wave-like cloud patterns in the sky, or billowing clouds.
Different layers of the atmosphere can have different densities with air moving at different speeds. This can create turbulence between layers. This turbulence can cause the formation of a wave pattern, similar to how air traveling over a lake can create ripples on the water.
At the surface this morning, winds were light to almost calm. However, if you were to be in an airplane, the winds at 32,000 feet were zipping by at over 100mph. The morning weather balloon launched from the National Weather Service in Blacksburg recorded winds winds at 120 knots, or 138 mph.
In the atmosphere, when one layer of air sits above a still cloud layer, it will create ripples as the stronger wind "scoops" up the clouds, causing them to turn into a wave pattern.
HOW RARE ARE THEY?
These clouds aren't that rare at all, but we do need the perfect conditions for them to form. Our winds aloft are quite strong, while at the surface are much lighter.
They were likely even more pronounced overnight when it was dark, we just couldn't see them.
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