Night Shining Clouds
Whispy noctilucent clouds are made of ice chyrstals and drift about 50 miles above Earth. They are too delicate and distant to be illuminated by daylight, but come nightfall these high clouds are struck with the steep post-sunset rays.
Night shining clouds are most commonly spotted in Northern Summer time skies and require -200°F temperatures in upper level air. Warmer months result in upwelling of polar air and the formation of noctilucent clouds.
“The reason it is cold during summer is somewhat complex,” said atmospheric cheist Dan Marsh of US National Center for Atmospheric Research. ”Ascending air cools, and as it does, the water vapor in the air condenses to form ice clouds.”
Scientists speculate the increase in noctilucent clouds is due to climate change. Rising CO2 may cool the upper level of the sky and rising methane creates more water vapor. These may both result in increased formation of night shining clouds. This phenomenon in the Northern skies is quite the spectacle for observers and atmospheric scientists alike.