Saturday, June 20, 2020

Amazing Noctilucent Clouds

One of the most extraordinary and beautiful sights this time of year are the delicate noctilucent clouds that can appear after sunset and before sunrise.

Take a look at a video made by Greg Johnson of Skunk Bay weather showing the celestial show yesterday morning:



Noctilucent clouds are the highest visible clouds, located around 50 miles above the earth surface. Such clouds form when moisture is deposited on dust in the upper atmosphere, generally from meteoritic dust.  Major volcanic ejections can also supply the small particles.

These cloud form in the layer of the atmosphere called the mesophere, where the temperatures are the coldest in the atmosphere.  Specifically, we are talking about temperatures below approximately -185F.   Midsummer is favored because paradoxically that is when the mesosphere is coldest.

NASA even has a satellite (AIM) dedicated to seeing these clouds, as illustrated by an example from June 13th below:


The first report of noctilucent clouds was in 1885 and a number of studies suggest that such clouds are getting more frequent.  

Human's may well have contributed to this increase.  But how?  

It appears that increasing human emission of methane (CH4) into the atmosphere (see below) may be the major cause, with methane breaking down in the upper atmosphere into several components, including water vapor.  More water vapor leads to enhanced ice cloud formation in upper atmosphere.


Another example of the profound effects of human activities on the environment.






9 comments:

  1. Another weather feature I have observed explained. Thanks. Off topic: Is anyone else having trouble accessing the Zone forecast page. I am now getting a "Forbidden you don't have permission to access this resource" response.

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  2. Strongly question the graph showing hockey-stick style increases in atmospheric methane since the year 1000! How was it measured for the past 1000 years?

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    1. Ice cores from polar regions.

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    2. Maybe an assumed level based on pre-Industrial Revolution situation?

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  3. I don't suppose this is related to the massive dust cloud coming from the Sahara since that shouldn't have reached the west by now, but I wonder if any of the particles in the mesosphere might be related.

    https://www.newsweek.com/sahara-dust-states-sunsets-1512163

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  4. That's fascinating. Thanks! Note that according to most research, a great deal of methane in the atmosphere originates in wetlands (rotting vegetation).

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  5. Thank you for sharing the beautiful video! Noctilucent cloud location in the mesosphere seems so far away. Are these true clouds? They seem alien, little understood. (Your blog sent me all over the internet.) Maybe God just likes messing with us.

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  6. Cliff,

    Beautiful--I always like Skunk Bay videos. Happy Father's Day!

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