We have a couple of interesting posts on noctilucent clouds at the South Pole.
At http://phys.org/print263633588.html … astronauts on the International Space Station took some pictures of noctilucent clouds over the top of the atmosphere. These blue ripples are distinctive and the claim is that they come from outer space – meteor smoke. The theory is that meteor dust is the nucleating aspect around which noctilucent clouds form. Originally, it was thought volcanic dust was involved but the clouds did not go away – they came back every year. Space dust is therefore thought to be the culprit and yet, there is a problem with this theory as noctilucent clouds have been spotted as far south as Colorado and Nebraska – and sometimes appear anomalously early in the year. Now we have a new theory, and climate change is being blamed. It is due to higher levels of methane in the atmosphere – or that is how it was spelt out.
At http://phys.org/print290065758.html … again, concerns noctilucent clouds – and here we are told they are getting earlier and earlier.
At http://phys.org/print307093711.html … we have the latest post on the subject and looking at the image above, we can see them forming above the South Pole (NASA image). They are compared with a geophysical light bulb as they turn up in late spring (in the southern hemisphere) and reach full intensity very quickly, blanketing the South Pole. Again, climate change is mentioned, and methane. It may well be time to take a peak at Tim Cullen's web site http://malagabay.wordpress.com and see what he has to say about methane – and it is substantial.