News
By Joel Gratz, Founding Meteorologist Posted 12 years ago November 16, 2011
Mountain waves
Ok, listen up all you nerds out there. Here's a little ditty about the strong winds and mountain waves we had over the weekend.
Think of the airflow over the Rockies as similar to water flowing down a rocky stream. As the water flows down the stream, it's bounced up and over and around the rocks, and then there are rapids.
The same thing happens in the atmosphere. As the air gets bounced up over and around the Rockies, there are rapids. Except you usually cannot see the rapids. If there is some moisture around, you might see the "white caps" of these rapids in the form of lenticular clouds, but if there is little moisture, you won't see the rapids because they won't form clouds.
However, some satellite images don't just detect clouds. They also detect water vapor. The cool thing about water vapor is that it's everywhere. Even when conditions aren't right to form clouds, there's still (invisible) water vapor in the air. And in this water vapor, you can see the rapids in the air, downstream of the Rockies.
Here's a visible satellite image from Saturday (Nov 12th) afternoon. White = clouds (or snow).
And here's the water vapor image at the same time.
Look at the area in east-central Colorado, near the blue "280 ^". This is an aircraft report of turbulence, and you can see why. While the visible satellite image at the top showed no clouds, you can clearly see the ripples (or "rapids") in the airflow from the lower water vapor image. Again, the bottom image is showing areas of more water vapor (blue) vs. less water vapor (yellow).
All areas where you see ripples on the bottom image and see no clouds on the upper image are areas of "clear air turbulence", where aircraft would be rocked around but there would be no warning signs because there are no clouds.
Pretty cool, eh? More about mountains waves on the CIMMS Satellite Blog (and thanks to them for the images!).
Think of the airflow over the Rockies as similar to water flowing down a rocky stream. As the water flows down the stream, it's bounced up and over and around the rocks, and then there are rapids.
The same thing happens in the atmosphere. As the air gets bounced up over and around the Rockies, there are rapids. Except you usually cannot see the rapids. If there is some moisture around, you might see the "white caps" of these rapids in the form of lenticular clouds, but if there is little moisture, you won't see the rapids because they won't form clouds.
However, some satellite images don't just detect clouds. They also detect water vapor. The cool thing about water vapor is that it's everywhere. Even when conditions aren't right to form clouds, there's still (invisible) water vapor in the air. And in this water vapor, you can see the rapids in the air, downstream of the Rockies.
Here's a visible satellite image from Saturday (Nov 12th) afternoon. White = clouds (or snow).
And here's the water vapor image at the same time.
Look at the area in east-central Colorado, near the blue "280 ^". This is an aircraft report of turbulence, and you can see why. While the visible satellite image at the top showed no clouds, you can clearly see the ripples (or "rapids") in the airflow from the lower water vapor image. Again, the bottom image is showing areas of more water vapor (blue) vs. less water vapor (yellow).
All areas where you see ripples on the bottom image and see no clouds on the upper image are areas of "clear air turbulence", where aircraft would be rocked around but there would be no warning signs because there are no clouds.
Pretty cool, eh? More about mountains waves on the CIMMS Satellite Blog (and thanks to them for the images!).
About The Author
Joel Gratz
Founding Meteorologist
Joel Gratz is the Founding Meteorologist of OpenSnow and has lived in Boulder, Colorado since 2003. Before moving to Colorado, he spent his childhood as a (not very fast) ski racer in eastern Pennsylvania.
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