Winter in the northern hemisphere, translates into summer in the southern hemisphere.
That also signals the arrival of bright blue clouds over Antarctica.
These are knows as noctilucent clouds.
NASA reports on November 20th, the Aeronomy of Ice in the Mesophere (AIM) spacecraft spotted the first of the clouds, which quickly expanded over nearly the entire continent.
Check out this movie of the clouds.
Noctilucent clouds are high clouds that are seeded by meteoroids.
The meteoroids break apart as they hit the Earth's atmosphere leaving behind tiny particles on which ice condenses.
NASA says "When sunlight hits the tiny ice crystals that make up these clouds, they appear to glow electric blue."
Previously, noctilucent clouds were only reported near the poles, but according to NASA recent reports placed these clouds near Colorado and Utah as well.
"Some researchers believe this is a sign of climate change. One of the greenhouse gases that has become more abundant in Earth's atmosphere since the 19th century is methane." says NASA.
Complex chemical reactions associated with the methane create water vapor.
The resulting increased water vapor content high in the atmosphere could be resulting in more noctilucent clouds.
A graphic below prepared by Prof. James Russell of Hampton University shows how methane, a greenhouse gas, boosts the abundance of water at the top of Earth's atmosphere. This water freezes around "meteor smoke" to form icy noctilucent clouds. [Larger image]
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