It used to be that you could only see these shimmering cloud formations, called noctilucent clouds, if you were in the north or south pole. But they've been on the move lately. Although they're pretty to look at, their presence away from the poles may be sign of climate change.
The clouds are appearing earlier than usual and closer to the equator, so the National Center for Atmospheric Research has been monitoring them since 2009. And AIM, the satellite NASA uses to look at clouds, has returned new data indicating that climate change is contributing to noctilucent cloud visibility.
Usually the clouds can only be observed from the Poles because summer warming melts ice caps slightly, pushing extra water vapor into the upper atmosphere. This vapuor than crystallises into ice and forms the noctilucent clouds. But scientists suspect that the clouds are forming over areas that don't have melting ice because excess methane from human activities is reacting chemically in the upper atmosphere to produce water vapour that normally isn't there. Enjoy the clouds (and the Earth) while you can. [Wired]
Picture: Brian Whittaker/NASA