Gitche Manitou
Posted on 06/11/2019 1:57:56 PM PDT by ProtectOurFreedom
Over the next few weeks, mid-latitude observers might experience the best noctilucent cloud viewing of their lifetimes.
Observers over the northern half of the U.S. are reporting something they have never seen before — electric-blue noctilucent (night-shining) clouds. They are wispy in appearance, and continuously change shape. They can be seen when the sun is about 6 to 16 deg. below the horizon, so about 1 to 2 hours after sunset or before sunrise. During that time of night the sun is still shining on these clouds, but not on any normal weather-related clouds.
In the late spring every year, people at far northern latitudes have often seen these on clear or partly-cloudy evenings. But solar-minimum conditions, with few if any sunspots, are causing cooling in the extreme upper atmosphere 50 miles high where the lowest atmospheric temperatures are recorded, approaching -150 F. That altitude is above 99.999% of the air in the atmosphere.
The wispy and undulating appearance of the clouds is due to upward-propagating gravity (air density) waves that cause temperatures to rise and fall, and the clouds form in the colder portions of those waves. Ice grows on meteor dust particles, creating a (nearly) outer space version of cirrus clouds. Time lapse photography has been used to show how the clouds change shape as the gravity waves well up through the extremely cold upper mesosphere:
If you miss seeing them in the next several weeks, take heart — solar minimum conditions should persist until the next NLC season arrives, making the summer of 2020 a good viewing opportunity, too.
(Excerpt) Read more at drroyspencer.com ...
That’s where the photos I posted came from.
Yep, that’s her, Noctilucent Cloud, almost as powerful as White Buffalo Calf Woman!
https://www.crystalinks.com/buffalocalfwoman.html
All we have to do is create the mythology for Noctilucent Cloud WoMAN!
Wow! Beautiful. Thanks for posting about this.
Glad you liked it. I thought it was something different and very cool.
...not to be confused with mating Mayflies.
Gitche Manitou
Grand solar minimum stuff. Keep your parka close at hand.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.