I'm a reader, writer and troublemaker. Sometimes I take photos and make time lapse movies too.
By: polymorph , 5:56 PM GMT on December 29, 2012
When I posted this photo I was unsure what to call the wave patterns I periodically observe with my camera at night. You can see the waves most clearly nearest to the horizon, though I think the pattern continues up to the top of the frame where the troughs are apparently spaced further apart (probably an optical illusion).
It seems that these are gravity waves, an entirely new phenomenon to me. Wikipedia says:
In the Earth's atmosphere, gravity waves are a mechanism for the transfer of momentum from the troposphere to the stratosphere. Gravity waves are generated in the troposphere by frontal systems or by airflow over mountains. At first, waves propagate through the atmosphere without appreciable change in mean velocity. But as the waves reach more rarefied air at higher altitudes, their amplitude increases, and nonlinear effects cause the waves to break, transferring their momentum to the mean flow.
This process plays a key role in controlling the dynamics of the middle atmosphere.
The clouds in gravity waves can look like altostratus undulatus clouds, and are sometimes confused with them, but the formation mechanism is different.
This link also helped me understand what they are a little better.
I found this cool time lapse while researching also:
Comments will take a few seconds to appear.