MessageToEagle.com – These mysterious, electric glowing clouds are beautiful to watch, but scientists believe they could be dangerous to our planet.
They were previously only seen over almost exclusively in Earth’s polar regions, but they are now also visible in the skies over the United States and Europe and else where. There is no doubt any more. The clouds at the edge of space are spreading.
The clouds are called noctilucent or “night-shining” clouds (NLCs) and they are a relatively new phenomenon.
“They were first seen in 1885″ about two years after the powerful eruption of Krakatoa hurled plumes of volcanic ash as much as 80 km high in Earth’s atmosphere,” says Gary Thomas, a professor at the University of Colorado who studies NLCs.
When the ash from the volcano settled and the vivid sunsets of Krakatoa faded, the noctilucent clouds were still there.
“It’s puzzling,” says Thomas. “Noctilucent clouds have not only persisted, but also spread.” A century ago the clouds were confined to latitudes above 50o; you had to go to places like Scandinavia, Russia and Britain to see them. In recent years they have been sighted as far south as Utah and Colorado.
“Although NLCs look like they’re in space,” continues Thomas, “they’re really inside Earth’s atmosphere, in a layer called the mesosphere ranging from 50 to 85 km high.”
The mesosphere is not only very cold (-125 C), but also very dry–“one hundred million times dryer than air from the Sahara desert.”
Nevertheless, NLCs are made of water. The clouds consist of tiny ice crystals about the size of particles in cigarette smoke.
How ice crystals form in the arid mesosphere is the essential mystery of noctilucent clouds.
No observations of anything resembling noctilucent clouds before 1885 has ever been found.
Why are they getting more numerous? Why are these clouds getting brighter and why are they appearing at lower latitudes?
Are the clouds a result of global warming? Could we human be responsible for their sudden appearance?
“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.
“The prevailing theory and most plausible explanation is that CO2 buildup, at 50 miles above the surface, would cause the temperature decrease,” Russell said. He cautioned, however, that temperature observations remain inconclusive.
The global changes that appear to be reshaping noctilucent cloud distribution could be much more complex, said Vincent Wickwar, an atmospheric scientist at Utah State University whose team was first to report a mid-latitude noctilucent cloud in 2002. Temperature does not explain their observations from around 42 degrees latitude.
“To get the noctilucent clouds you need temperatures that are about 20 degrees Kelvin colder than what we see on average up there,” Wickwar said. “We may have effects from CO2 or methane but it would only be a degree or a fraction of a degree.”
“I suspect, as many of us feel, that it is global change, but I fear we don’t understand it,” Wickwar said. “It’s not as simple as a temperature change.” For now scientists are left with more questions exist than firm answers.