(meteorobs) Fwd: "meteor smoke" is essential to the formation of noctilucent clouds.

[Marco Langbroek]

Op 7-8-2012 5:47, Richard Kramer schreef:
> At 07:40 PM 8/6/2012, you wrote:
>> Methane is a powerful greenhouse gas and is estimated to be responsible for
>> approximately one-fifth of man-made global warming. Per kilogram, it is 25
>> times more powerful than carbon dioxide over a 100-year time horizon .
>
> OK, so how does this make climate change responsible for noctilucent
> clouds at lower latitudes?


Climate change and NLC are both the *result* of increased Methane emissions.

While you are right insofar as it is the methane causing the increase in NLC and 
not climate change causing this itself (but wait: see below, it does so with a 
twist after all!), the two nevertheless are closely connected. More methane = 
rising greenhouse effect *and* more NLC.

Moreover, with a twist climate change *is* in fact directly contributing to 
rising atmospheric methane levels. As a result of a warmer climate, permafrost 
disappears. As permafrost melts, methane contained in the formerly frozen 
deposits dissipates into the atmosphere. And yes: the quantities in question are 
large, this is not some minor process. It is seen as a serious positive feedback 
mechanism in post-glacial warming.

So they worded it a bit convoluted, but basically they are right: there is a 
connection between climate change and rising NLC visibility. Both could be the 
result of rising atmospheric methane levels (and part of the latter *is* the 
direct result of a warming climate).

In that sense, these remarks were *not* gratuitous at all.

What bothered me more is that they glossed over a number of earlier studies 
connecting NLC formation to micrometeoroid particles. It is not such a 'new' 
insight as it was suggested in the video. A friend of mine (Frans Rietmeijer, an 
IDP specialist at UNM) has been publishing a number of papers on this over the 
past 20 years, and in fact the idea is around since the sixties already.

Also, I am cautious as to whether NLC occurrences are really on the rise. You 
cannot exclude that the rise in sighting reports is an autofeedback due to a 
rising awareness of the phenomena. People don't see things if they don't look 
for it.

- Marco


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Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)

e-mail: dms at marcolangbroek.nl
http://www.dmsweb.org
http://www.marcolangbroek.nl
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