Showing posts with label Noctilucent Clouds. Show all posts
Showing posts with label Noctilucent Clouds. Show all posts
Monday, July 07, 2014
Mysterious Night-Shining Clouds Glow Above Northern Ireland
Electric-blue noctilucent clouds glimmered in the sky just before dawn when this amazing image was captured.
Astrophotographer John McConnell took the photo on June 20, 2014 from Maghaberry, Northern Ireland.
Noctilucent clouds or NLCs are blue-white clouds that are so bright they can be seen in the twilight sky. They typically form about 50 to 53 miles (80 and 85 kilometers) above ground in the atmosphere, at altitudes high enough to reflect light even after the sun has slipped below the horizon.
"This was the best display since the 2009 season . . ..
Monday, June 23, 2014
Mysterious 'Noctilucent' Clouds Have Returned
By Joe Rao
Space.com
6-22-14
Earth's polar skies have shined with eerie blue-white glowing clouds slowly twisting and undulating in the twilight sky every summer since the late 19th century.
These mystifying clouds are referred to as night-shining or noctilucent clouds. Such clouds form in an upper layer of the Earth’s atmosphere called the mesosphere during the summer and can be seen from the high latitudes on Earth.
If skywatchers want to possibly see noctilucent clouds, four criteria must be met: The sky must be free of tropospheric ("ordinary") clouds. The region of the atmosphere where they form must be sunlit. This means that the sun must be no more than 16 degrees below the horizon. The background sky must be adequately dark enough for the clouds to stand out. This final requirement means that the sun must be at least 6 degrees below the horizon, what astronomers refer to as the end of civil twilight. Your viewing location should be at a latitude north of 45 degrees, although as you will soon see the clouds have been sighted at more southerly latitudes in recent years.
Sunday, July 03, 2011
Night-Shining Clouds (NLCs) Sighted over the United States
NLCs INVADE THE USA
On July 1st and 2nd, a bank of rippling electric-blue noctilucent clouds spilled across the Canadian border into the lower United States. In doing so, the clouds made their farthest excursion of the year away from the Arctic, their usual environment. "These were the most brilliant NLCs I have ever witnessed!" reports Steven Rosenow . . . .
