At first people thought they were a side-effect of the volcano, but long after Krakatau’s ash settled, the wispy, glowing clouds remained. The early start in 2013 is puzzling because of the solar cycle. You can view a daily composite projection of noctilucent clouds by clicking here during the northern summer months. The International Space Station Program supports the laboratory to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. The image on the upper right shows noctilucent clouds on May 23, 2013; the upper left image compares the same week from 2012. Our ability to study these connections will surely lead to new understanding about how our atmosphere works.”. Extremely cold and wet conditions in the mesosphere have led to abundant noctilucent clouds. Atmosphere. Zahn, U. , Are Noctilucent Clouds Truly a “Miner’s Canary” for Global Change?. Video by Science@NASA. This year, noctilucent clouds (NLCs) got an early start; NASA’s Aeronomy of Ice in the Mesosphere (AIM) spacecraft first saw them on May 13. Image of the Day As spring turns to summer in the northern hemisphere, unusual streaks of clouds form high in the atmosphere around sunset. Atmosphere Researchers have previously observed that noctilucent clouds seem to peak during solar minimum and become scarce during solar maximum. “When methane makes its way into the upper atmosphere, it is oxidized by a complex series of reactions to form water vapor,” Russell said. Noctilucent Clouds taken from 36,000 feet above the South of Nunivak Island, Alaska on June 20, 2006. Flight Center. Polar Mesospheric Clouds Over Central Asia, NASA Goddard Space Some researchers assert that this is a sign of greenhouse warming, as methane has become more abundant in Earth’s atmosphere. Flight Center, NASA Earth Observatory (2013, January 21), NASA Earth Observatory (2011, January 27). AIM has quickly filled in the gaps. Areas with no data appear in black, and coastal outlines are traced in white. NASA’s Aeronomy of Ice in the Mesosphere spacecraft — AIM for short — first spotted wisps of these noctilucent, or night-shining, clouds over the Arctic on May 17. When AIM was launched in 2007, the cause of noctilucent clouds was still unknown. This image was taken July 27, 2003 when the ISS was over central Asia. Ice crystals begin to cling to dust and particles high in the atmosphere, forming electric-blue, rippled clouds that stretch across the sky at sunset. Noctilucent or “night-shining” clouds are a delight for high-latitude sky watchers, and their season is eagerly anticipated around the Arctic Circle. Atmosphere. The silvery-blue noctilucent clouds are far above this boundary. Strange, Glowing Night Clouds Continue to Spread. Image of the Day The sliver of the setting moon and clouds that shine at night—noctilucent clouds—caught the eye of astronaut Ed Lu aboard the International Space Station (ISS) last week. A View of Noctilucent Clouds over Earth's Polar Regions Most recent image of Noctilucent Clouds (NLCs) over one of the polar regions. The warmest months in the troposphere (lower atmosphere) are also the coldest in the mesosphere (where NLCs form). Astronauts and cosmonauts have observed them over northern latitudes (Europe, Russia) in the past, but this summer’s display has been remarkable. Data from NASA’s Aeronomy of Ice in the Mesosphere, or AIM, spacecraft shows the sky over Antarctica is … “But now NLCs are teaching us about connections between different layers of the atmosphere that operate over great distances. Animation by Robert Simmon, using data from LASP/University of Colorado. Night-Shining Clouds Are Getting Brighter. Noctilucent clouds are very high clouds that look like cirrus clouds, but are much higher (75-90 km above the Earth’s surface) than clouds that we observe every day. As spring turns to summer in the northern hemisphere, unusual streaks of clouds form high in the atmosphere around sunset. The images above show Earth’s upper atmosphere, centered on the North Pole, as observed by the AIM satellite. They are illuminated by sunlight when the lower layers of the atmosphere are in the darkness of Earth’s shadow. In the northern hemisphere, night-shining clouds seem to be forming earlier and spreading farther each year, as they did in 2013.