July 30, 2023

A Summer of Beautiful Cirrus Clouds

This has been an interesting summer in many ways, with a persistent offshore upper-level trough resulting in temperatures averaging a bit higher than normal, but with a lack of major heatwaves. 

But there is more.  The offshore upper-level trough has produced upward motion in the upper troposphere (roughly 15,000 to 35,000 ft) that has produced ice clouds.

These are cirrus clouds of various forms, and they are often very beautiful.  Let me share a few pictures with you.

Below is a picture taken last night near sunset.  Ice crystals are actually falling out of some of the cirrus clouds and bending back due to the weaker winds at lower levels.

These features are called fallstreaks.  Often called mare's tails.


Or if you want something really fancy, here is a circular cirrus cloud complex with a fallstreak in the middle.   Could be mistaken, perhaps, for a UFO.


By the way, one way you can tell you are looking at an ice crystal cloud is that the boundaries of the cloud are fuzzy and not sharp.

Sometimes cirrus forms in complex linear features:


And if there is enough change in wind speed with height, the cirrus can be distorted into wave-like features associated with the impressive-sounding name, Kelvin-Helmholtz instability:


What do cirrus clouds look like from space?   Here is a recent example showing lots of cirrus clouds over the South Sound.


Finally, this is one type of ice crystal cloud that is less frequent over western Washington than over the eastern half of the U.S.:  cirrus anvil clouds associated with vigorous thunderstorms.   I did catch an example of one associated with a thunderstorm over the Cascades (below).  You see the flat upper portion of the thunderstorm....that is the cirrus anvil.


Enjoy your cirrus viewing.

Reminder:  There is an online zoom session for Patreon supporters tonight!


4 comments:

  1. I'm still wondering about your take on the melting glaciers. Now they say Antarctica is in trouble as well.

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    1. Glaciers have been melting for about 150 years due to the end of the Little Ice Age. During the past 30-50 years, human-induced warming from co2 emissions have been contributing as well. Antarctic ice is fine....there have been some stories about sea ice loss near that continent.

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  2. These are gorgeous. We haven't had anything quite that good up north.
    I'd be jealous of that thunderhead, but at least our electronics don't get fried all the time here.

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  3. not just a summer of wonderful clouds. we are having the PERFECT summer. perfect daytime temps, nice sleep inducing night time temps. hard to relate to the apocolypse headlines.

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