Altostratus Undulatus Or Gravity Wave Clouds?

Yesterday afternoon, from horizon to horizon, the high level clouds were lined up like rows.

I’ve seen this before, but there are two types of clouds that can form this way – altostratus undulatus clouds or gravity wave clouds.

“Gravity wave” clouds sound just absolutely bitchin’ and when I first heard the term I was hoping it was a manifest, macro-scale effect in our atmosphere from the sort of gravity waves that are just now being detected from colliding black holes. I wanted an unbelievably huge release of energy a hundred thousand years ago and a hundred thousand light years away to making patterns in our sky.

It doesn’t.

Instead, “gravity wave” clouds are formed the same way that the wind whipping over the ocean forms ocean waves. It’s a matter of buoyancy differences in a fluid in motion causing oscillations in the fluid flow. Still cool, but not black-hole-collision-drawing-patterns-in-our-sky cool.

This could also be (and most likely are) altostratus undulatus clouds, which are wispy clouds of ice, high in the atmosphere, which forms bands like this as they flow over mountains or coastlines which disrupt the smooth flow of a weather front. We had a a front moving in, there’s a coastline over to our west, and these are wispy clouds of ice, high in the atmosphere.

My money’s on altostratus undulatus.

Either way – cool looking clouds.

And if you click on them and blow them up to full-sized, can you see the tiny sliver of the crescent moon in the upper left corner of one?

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