Maybe climate change isn’t all bad…

Increased water vapor in Earth’s atmosphere, a consequence of human activity, makes shimmering, high-altitude clouds more visible.

Noctilucent, or night-shining, clouds form some 50 miles above the planet’s surface, when water vapor freezes around specs of dust from incoming meteors.

It sounds oddly romantic.

The first noted observation of noctilucent clouds came after the 1885 eruption of the Krakatoa volcano, which spewed massive amounts of water vapor into the air.

Sightings became more common in the 20th century, and by the 1990s, scientists began to wonder whether climate change was to blame.

“We speculate that the clouds have always been there, but the chance to see one was very, very poor, in historical times,” according to lead study author Franz-Josef Lübken, an atmospheric scientist at the Leibniz Institute of Atmospheric Physics in Kühlungsborn, Germany.

Using satellite observations and climate models, researchers simulated how increased greenhouse gases from burning fossil fuels contributed to the formation of night-shining clouds over the past 150 years.

Methane emissions in particular have increased water vapor concentrations in the mesosphere by 40 percent since the late 1800s.

“Our methane emissions are impacting the atmosphere beyond just temperature change and chemical composition,” Ilissa Seroka, an atmospheric scientist at the Environmental Defense Fund in Washington, D.C., told the American Geophysical Union (AGU).

Noctilucent clouds over the city of Wismar, Germany in July 2015 (via Leibniz Institute of Atmospheric Physics)

“We now detect a distinct response in clouds,” Seroka, who was not involved in the study, said.

Don’t expect to spot puffs of noctilucent smoke every night this season. Unlike the cumulus, stratus, cirrus, and nimbus clouds that form less than 10 miles in the sky, the night-shining phenomenon exists above the ozone layer, weather balloons, and meteors, where temperatures must be cold enough for ice crystals to form.

And, they’re only visible at dawn and dusk, when the Sun illuminates them from below the horizon.

Still, if photos are anything to go by, noctilucent clouds are a spectacle I am adding to my bucket list.


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