"Ripcurl has upped their ad campaign," a lady commented when spectacular clouds appeared like waves in the sky across the Far South Coast.
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The clouds crossed the sky looking like a row of crashing waves on the beach, and caught residents off guard when they appeared at sunset.
The cloud formation is due to Kelvin-Helmholtz instability - an element of fluid dynamics.
Meteorologist Miriam Bradbury from the Bureau of Meteorology said the main thing leading to clouds forming in this way was called wind shear.
"It is essentially when wind at two different levels in the atmosphere is moving at a different speed or a different direction," Ms Bradbury said.
"In the case of these clouds, we have wind moving a bit slower at the bottom, and wind moving a bit faster at the top.
![Stunning wave-shaped clouds on the way to Bega. Picture by Mandy Macleod Stunning wave-shaped clouds on the way to Bega. Picture by Mandy Macleod](/images/transform/v1/crop/frm/205490442/80b46991-6930-4d05-80d3-9e58059df3ce.jpg/r0_354_2016_1487_w1200_h678_fmax.jpg)
"What that's doing is when these clouds are forming, moving upwards, that faster wind at the top is knocking the top over."
Ms Bradbury explained it like a tower made from blocks, and when both the top and bottom of the tower are pushed in the same direction, it would stay intact.
"When you give the tower a big shove and leave the bottom of the tower where it is, it's just going to topple over, and that's essentially what we're seeing in the atmosphere [in these photographs]," she said.
![The clouds were a surprising addition to an evening drive home. Picture by Mandy Macleod The clouds were a surprising addition to an evening drive home. Picture by Mandy Macleod](/images/transform/v1/crop/frm/205490442/6ef891d4-1ac6-4d38-9431-f205552805c2.JPG/r278_591_1685_1357_w1200_h678_fmax.jpg)
"The atmosphere is what we call a fluid, so it acts like a fluid rather than something dry, and that's why we see the same patterns forming in the ocean as we do in the air."
While they are not uncommon, Ms Bradbury said the best chance to capture them was at sunrise or sunset when the air can be less or more dense.
"It depends how you categorise common, once every 10 years could be uncommon, but once a year could also be uncommon," she said, having spotted them approximately three times per year.
"It's like a rainbow or a solar halo, something like that, they're not terribly uncommon, but they're special to see."
Do you have some spectacular weather or cloud photographs? Email them to james.parker@austcommunitymedia.com.au