Photo by Dave Lacey of South Coast Tours.

Rare wave-like clouds known as Kelvin-Helmholtz clouds were spotted above Brookings last week.

Tour guide Dave Lacey of South Coast Tours, the same folks who captured the mola mola sighting near Thomas Creek Bridge earlier this month, took this photo of the clouds on Friday.

Meteorologist Brad Schaaf of Medford’s National Weather Service office told the Outpost that the clouds are a rare sight.

“They can happen, they're pretty rare though, so the person who got the picture is pretty lucky,” Schaaf said.

Schaaf said the process is difficult to explain, but that the clouds are basically formed through the same process as ocean waves.

"The winds at the tops of the clouds are moving faster than the winds at the bottom," he said. "It’s causing the cloud to drift away from itself like a wave. The same thing happens with ocean waves when they reach the shore, you’re just seeing it in the air."

After being swept up by the faster wind speeds, the cloud eventually crests and falls just like waves you'd see at the beach.

“When wind blows over water and creates a wave, the wave gets to the point where the ground affects it and you start to get the big crests,” Schaaf said. “It’s basically an instability in the wave, when it gets too much, the wave will break.”

For more information about Kelvin-Helmholtz clouds, see the videos below.

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