Mysterious Night-Shining Clouds

From National Geographic.

The noctilucent clouds form in the upper layer of the Earth's atmosphere in summer and are made of tiny ice crystals.

Scientists don't know much about how the clouds form, or why they have been appearing more often at lower latitudes and glowing brighter. Some scientists suspect their proliferation is related to increasing greenhouse gases, which can actually cause the upper reaches of the atmosphere to cool.

The amount of water vapour in the upper atmosphere has increased in the past 50 years, perhaps as a result of increased methane in the atmosphere from farming and other human activities. Methane can react with oxygen in the atmosphere to create water molecules.

To find out, NASA has employed a satellite, named AIM (Aeronomy of Ice in Mesosphere) to observe two cloud seasons over both of Earth's Poles. On June 11, AIM captured its first images of night shining clouds. The satellite will also provide scientists with data on the size and shape of the particles that make up the clouds.

Related: Satellite snaps first images of mysterious glowing clouds.


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