Noctilucent Clouds
Thread Starter
Joined: Apr 2000
Posts: 963
Likes: 43
From: 30 West
Noctilucent Clouds
Ladies and Gentlemen of the Atlantic !
I told you last night that I would give more information about the spectacular display of Noctilucent cloud as we all crossed the pond last night.
Despite having to s...p...e...l...l it really slowly for our Southern Cousin, I hope you got the gist of what it was about. Anyway, here is more
Noctilucent clouds, also known as polar mesospheric clouds are bright cloudlike atmospheric phenomena visible in a deep twilight. The name means roughly "night shining" in the Latin language. They are most commonly observed in the summer months at latitudes between 50° and 60° north and south of the equator.
They are the highest clouds in the Earth's atmosphere, located in the mesosphere at altitudes of around 85 km, and are visible only when illuminated by sunlight from below the horizon while the ground and lower layers of the atmosphere are in the Earth's shadow; otherwise they are too faint to be seen. Noctilucent clouds are not fully understood, as under most understood meteorological concepts, clouds generally are not able to reach such high altitudes, especially under such thin air pressures.
As an explanation, it was once proposed that they were composed of volcanic or meteoric dust, but they are now known to be primarily composed of water ice (confirmed by UARS). They appear to be a relatively recent phenomenon—they were first reported in 1885, shortly after the eruption of Krakatoa—and it has been suggested that they may be related to climate change. At least one researcher, Dr. Michael Stevens of the United States Naval Research Laboratory, believes space shuttle exhaust may contribute to the formation of noctilucent clouds. [1]
Noctilucent clouds can be studied from the ground, from space, and in situ by sounding rockets; they are too high to be reached by weather balloons. The AIM satellite mission, scheduled for launch in 2006, is dedicated to research into noctilucent clouds.
I told you last night that I would give more information about the spectacular display of Noctilucent cloud as we all crossed the pond last night.
Despite having to s...p...e...l...l it really slowly for our Southern Cousin, I hope you got the gist of what it was about. Anyway, here is more
Noctilucent clouds, also known as polar mesospheric clouds are bright cloudlike atmospheric phenomena visible in a deep twilight. The name means roughly "night shining" in the Latin language. They are most commonly observed in the summer months at latitudes between 50° and 60° north and south of the equator.
They are the highest clouds in the Earth's atmosphere, located in the mesosphere at altitudes of around 85 km, and are visible only when illuminated by sunlight from below the horizon while the ground and lower layers of the atmosphere are in the Earth's shadow; otherwise they are too faint to be seen. Noctilucent clouds are not fully understood, as under most understood meteorological concepts, clouds generally are not able to reach such high altitudes, especially under such thin air pressures.
As an explanation, it was once proposed that they were composed of volcanic or meteoric dust, but they are now known to be primarily composed of water ice (confirmed by UARS). They appear to be a relatively recent phenomenon—they were first reported in 1885, shortly after the eruption of Krakatoa—and it has been suggested that they may be related to climate change. At least one researcher, Dr. Michael Stevens of the United States Naval Research Laboratory, believes space shuttle exhaust may contribute to the formation of noctilucent clouds. [1]
Noctilucent clouds can be studied from the ground, from space, and in situ by sounding rockets; they are too high to be reached by weather balloons. The AIM satellite mission, scheduled for launch in 2006, is dedicated to research into noctilucent clouds.
Dog Tired
Joined: Oct 2001
Posts: 1,686
Likes: 2
From: uk
Ah yes, excellent sight. I was heading east-ish and droning on to the FO about the northern lights when I realised they were on the wrong side (south of us!). A lesson from one of our more learned captains put me right.
Do have a look for them next time you are heading home from Canada; a ghostly white, very high, mass of shapeless cloud. Good stuff, even if you can't spell it...
Do have a look for them next time you are heading home from Canada; a ghostly white, very high, mass of shapeless cloud. Good stuff, even if you can't spell it...
Joined: Jun 2001
Posts: 5,896
Likes: 1
From: Rockytop, Tennessee, USA
Despite having to s...p...e...l...l it really slowly for our Southern Cousin
...I saw the clouds over Denmark from FL390 around 2130Z last night, they were great. They appeared to be in the deep twilight of the sunset to the northwest.
Last month I saw a nice display over the UK in the northern glow that you get at those latitudes within a few weeks of the summer solstice.
Here are some other recent reports of sitings, including last night's display:
http://www.nlcnet.co.uk/nlcreps.htm#latest
Also, the Wikipedia article has some good links, some of the slowly spelled text from the first post on this thread seems to be lifted from this article without attribution:
http://en.wikipedia.org/wiki/Noctilucent_clouds
