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Electric-blue night clouds are invading the U.S.


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#1 Atossa

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Posted 12 June 2019 - 07:24 AM



Electric-blue night clouds are invading the U.S.



June 11th, 2019 by Roy W. Spencer, Ph. D.


Over the next few weeks, mid-latitude observers might experience the best noctilucent cloud viewing of their lifetimes.


Tucker-Shannon-IMG_20190609_215353_15602

Extremely high-altitude noctilucent (night-shining) clouds viewed from Corvallis, Oregon on June 10, 2019 (Tucker Shannon, Google Pixel phone).


Observers over the northern half of the United States 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 around 80 km (~50 miles) high where the lowest atmospheric temperatures are recorded, approaching -150 deg. F (-100 deg. C). That altitude is above 99.999% of the air in the atmosphere.


NLC-from-ISS-550x367.jpg

Noctilucent clouds observed from the International Space Station on June 13, 2012 (NASA).


Adding to the spectacular electric blue displays is increasing atmospheric methane, which gets converted to water vapor at these altitudes, and increasing atmospheric carbon dioxide, which causes enhanced cooling of the upper atmosphere. The result is that the conditions necessary for NLC formation are extending farther south than ever before.

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:


2017 NOCTILUCENT CLOUD CHASING SEASON TEASER 4K (UHD) from Night Lights Films on Vimeo.

See link for video


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.

You can see recent NLC photos from around the Northern Hemisphere, updated daily, here. "


http://www.drroyspen...vading-the-u-s/



Edited by Atossa, 12 June 2019 - 07:29 AM.

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#2 Zharkov

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Posted 12 June 2019 - 01:49 PM

"Fear Of The Dark"
 

I am a man who walks alone
And when I'm walking a dark road
At night or strolling through the park
When the light begins to change
I sometimes feel a little strange
A little anxious when it's dark

Fear of the dark, fear of the dark
I have a constant fear that something's always near
Fear of the dark, fear of the dark
I have a phobia that someone's always there

Have you run your fingers down the wall
And have you felt your neck skin crawl
When you're searching for the light?
Sometimes when you're scared to take a look
At the corner of the room
You've sensed that something's watching you

Fear of the dark, fear of the dark
I have a constant fear that something's always near
Fear of the dark, fear of the dark
I have a phobia that someone's always there

Have you ever been alone at night
Thought you heard footsteps behind
And turned around and no-one's there?
And as you quicken up your pace
You find it hard to look again
Because you're sure there's someone there

Fear of the dark, fear of the dark
I have a constant fear that something's always near
Fear of the dark, fear of the dark
I have a phobia that someone's always there

Fear of the dark, fear of the dark
Fear of the dark, fear of the dark

Fear of the dark, fear of the dark
Fear of the dark, fear of the dark

Watching horror films the night before
Debating witches and folklore
The unknown troubles on your mind
Maybe your mind is playing tricks
You sense, and suddenly eyes fix
On dancing shadows from behind

Fear of the dark, fear of the dark
I have a constant fear that something's always near
Fear of the dark, fear of the dark
I have a phobia that someone's always there

Fear of the dark, fear of the dark
I have a constant fear that something's always near
Fear of the dark, fear of the dark
I have a phobia that someone's always there

When I'm walking a dark road
I am a man who walks alone
 
-Iron Maiden
 
+++++++++++++++

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#3 Zharkov

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Posted 12 June 2019 - 01:53 PM


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#4 Ivan88

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Posted 12 June 2019 - 04:28 PM

Moon shining on high thin clouds.  Nice pictures.


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