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Noctilucent Clouds

July 27, 2015

If you live at high northern latitudes, you might see some eerie clouds at this time of year. They show up for a little while in deep twilight, and shine electric blue. And they appear to have a connection to both meteors and our planet’s changing climate.

Noctilucent clouds were first reported in 1885. That sighting may have been related to the eruption of Krakatoa, a powerful volcano in Indonesia. Tiny grains of ash from the explosion may have drifted to the top of the atmosphere — altitudes of 45 to 50 miles. Molecules of water then latched on to the ash particles, forming ice crystals.

But recent research suggests that most noctilucent clouds are seeded by tiny grains of space dust. These particles bombard our planet all the time. Many of them are so small that they don’t fall to the ground, but linger in the upper atmosphere. They form the kernels around which cloud particles grow.

Sightings of noctilucent clouds have become more common in recent years, and the clouds have been seen farther south than ever before — as far down as Utah and Colorado.

Research says that could be a result of the extra methane we release into the air every year. Some of the methane climbs to high altitudes. Sunlight triggers a series of reactions that breaks the methane apart, leaving two water molecules. That provides more water to freeze around the nuggets of space dust — creating more of these electric-blue clouds in the twilight.

Script by Damond Benningfield, Copyright 2015

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