[ATMoB-discuss] Noctilucent Clouds

Thu Jul 12 15:07:05 CEST 2007

There should soon be much more data on this phenomenon as NASA has just
had "first light" on the AIM Satellite:

Released image:
http://www.nasa.gov/images/content/181085main_AIMData_lg.jpg 
(Interestingly, as noted below, the activity seems to favor the Europe,
rather than the North America.)

Stories: 
http://www.nasa.gov/home/hqnews/2007/jun/HQ_07145_AIM_First_Light.html &
http://www.nasa.gov/mission_pages/aim/multimedia/first_view.html 
http://space.newscientist.com/article/dn12171-satellite-snaps-first-imag
es-of-mysterious-glowing-clouds.html 

Archive of images: http://www.polarx.net/NoctilucentClouds.htm 

NASA Satellite Captures First View of 'Night-Shining' Clouds

WASHINGTON -- A NASA satellite has captured the first occurrence this
summer of mysterious iridescent polar clouds that form 50 miles above
Earth's surface.

The first observations of these clouds by the Aeronomy of Ice in the
Mesosphere (AIM) satellite occurred above 70 degrees north on May 25.
Observers on the ground began seeing the clouds on June 6 over northern
Europe. AIM is the first satellite mission dedicated to the study of
these unusual clouds.

These mystifying clouds are called Polar Mesospheric Clouds, or PMCs,
when they are viewed from space and referred to as "night-shining"
clouds, or noctilucent clouds, when viewed by observers on Earth. The
clouds form during the Northern Hemisphere's summer season that begins
in mid-May and extends through the end of August. They are being seen by
AIM's instruments more frequently as the season progresses. The clouds
also are seen in the high latitudes of the Southern Hemisphere during
the summer months.

Very little is known about how these clouds form over the poles, why
they are being seen more frequently and at lower latitudes than ever
before, or why they have been growing brighter. AIM will observe two
complete polar mesospheric cloud seasons over both poles, documenting
for the first time the entire, complex life cycle of PMCs. 

"It is clear that PMCs are changing, a sign that a distant and rarified
part of our atmosphere is being altered, and we do not understand how,
why or what it means," stated AIM principal investigator James Russell
III, Hampton University, Hampton, Va. "These observations suggest a
connection with global change in the lower atmosphere and could
represent an early warning that our Earth's environment is being
altered."

The AIM instruments are returning valuable information on the global
extent and variability of these clouds and preliminary information on
their particle sizes and shapes. Early indications are that the clouds
occur at high latitudes early in the season then move to lower latitudes
as time progresses. The AIM science team is studying these new data to
understand whether the changes in the clouds may be related to global
climate change.

When the Northern Hemisphere summer season ends in mid- to late August,
the AIM science team will not have to wait long before the Southern
Hemisphere's season starts. This occurs about three months later in mid-
to late November. The Southern season lasts until approximately
mid-March of 2008. Early results from the AIM mission will be reported
at a major international conference focused on PMCs and other high
altitude layered phenomena to be held at the end of August 2007 in
Fairbanks, Alaska.

The satellite was launched on April 25, only four weeks before the first
science observations began. During the satellite-commissioning phase and
now in routine observations, all three state-of-the-art instruments have
been working exceptionally well and returning high quality data. 

The Cloud Imaging and Particle Size instrument offers a 2-D look at the
clouds, collecting multiple views from different angles. The cameras are
providing panoramic PMC images of the Arctic polar cap daily. The Solar
Occultation For Ice Experiment is measuring new information on cloud
particles: their variability with altitude, the chemicals within the
clouds and the environment in which the clouds form. The Cosmic Dust
Experiment is recording the amount of space dust that enters Earth's
atmosphere to help scientists assess the role this dust plays in PMC
formation.

The AIM mission coincides with the two-year, worldwide scientific
community's International Polar Year, and the mission is expected to
make unique contributions to the International Polar Year's objective of
advancing polar research.

AIM is the ninth Small Explorers mission under NASA's Explorer Program
and is managed by the Explorers Program Office at the Goddard Space
Flight Center, Greenbelt, Md. The AIM Project Data Center is located at
Hampton University.

For related images on this story, please visit:

http://www.nasa.gov/aim 

-Bruce Tinkler
(From my July Astronomy Update)

-----Original Message-----
From: atmob-discuss-bounces at atmob.org
[mailto:atmob-discuss-bounces at atmob.org] On Behalf Of Paul E. MacNeil
Sent: Thursday, July 12, 2007 8:30 AM
To: noatak at aol.com
Cc: atmob-discuss at atmob.org
Subject: Re: [ATMoB-discuss] Noctilucent Clouds

Mike,

    You may already be aware of this page and the "External Links" 
section at the end of it, but just in case, 
http://en.wikipedia.org/wiki/Noctilucent_cloud looks interesting.

    Good luck! Let us know what you see!

             Paul

noatak at aol.com wrote:
> I'm curious as to what people in the club think or know about
Noctilucent Clouds.
>
> There have been a lot of reports of sightings of these mysterious
clouds which form in the extreme
> upper atmosphere and are typically visible 1-2 hours after sunset in
the summer months. All of the reports
> lately tend to be from observers in europe and a couple last month in
the Western US. Nothing here however.
> Anyone wish to fathom a guess or post a logical reason why these might
be occuring there and not here.
>
> Is there a web site dedicated to this phenomenom that would allow a
search of past occurences and 
> corresponding locations by date?
>
> Has anyone seen this lately from the Eastern US?
>
> I do hope we get a display (on?a clear night). I would love to see
what appears to be quite an impressive
> sight rivaling a good auroral display.
>
>
> Mike Hill
>
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