EcoWorldly

My boss was in France on Bastille Day last week where the big event of the night actually became the sight of these strange glowing clouds - - like polar noctilucent clouds except they were not over the North Pole - but over Paris.

But Bastille Day celebrants were not the only ones to grab pictures of these strange new clouds.

Over the last week, photographers in many places around the world outside the Arctic regions, have run outside to get photos of these strange Noctilucent (Night Glowing) clouds showing up this week from Poland to North Dakota:

Formed by ice literally at the boundary where the earth’s atmosphere meets space 50 miles up, they shine because they are so high that they remain lit by the sun even after our star is below the horizon.

Noctilucent clouds are a fundamentally new phenomenon in the temperate mid-latitude sky, and it’s not clear why they’ve migrated down from the poles. Or why, over the last 25 years, more of them are appearing in the polar regions, too, and shining more brightly.

“That’s a real concern and question,” said James Russell, an atmospheric scientist at Hampton University and the principal investigator of an ongoing NASA satellite mission to study the clouds. “Why are they getting more numerous? Why are they getting brighter? Why are they appearing at lower latitudes?”

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Theories abound to explain the observed changes in the clouds.

Human-caused increases in atmospheric methane, which oxidizes into carbon dioxide and water vapor, could be providing more water for ice in the stratosphere. Increases in the amount of cosmic or terrestrial dust in the stratosphere could also increase the number of brightly shining clouds.

Noctilucent clouds were first observed in 1885, two years after the eruption of Krakatoa. It remains unclear whether their appearance had anything to do with the volcano, or whether their discovery was due to more people observing the spectacular sunsets caused by the volcanic debris in the atmosphere.

The fact that there have been no observations until 1885 suggests that there is a climate connection. Throughout the ages, people have noted any strange portends in the heavens.

For example this very big news about the 1521 comet is shown here being relayed to King Harold. This was woven into the permanent record. However, glowing clouds were not noted historically till after the Industrial Revolution.

Indeed, climate models have predicted that higher greenhouse gas emissions would cause mesosphere cooling, resulting in more frequent and widespread occurrences of noctilucent clouds.

But a competing theory is that larger methane emissions from intensive farming activities are producing more water vapour in the upper atmosphere where methane concentrations have more than doubled in the past 100 years.

Changes are occurring faster than scientists can understand their causes. Stay tuned.

Photos via kajekai and technobahn from Japan and Eve in Montana and Marek in Poland
Via Wired Science

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