Near Earth’s North and South poles, wispy, iridescent clouds often shimmer high in the summertime sky around dusk and dawn.
Near Earth’s North and South poles, wispy, iridescent clouds often shimmer high in the summertime sky around dusk and dawn. These night-shining, or noctilucent, clouds are sometimes spotted farther from the poles as well, at a rate that varies dramatically from year to year. According to a new study using NASA’s Aeronomy of Ice in the Mesosphere (AIM) satellite, which is managed by the Explorers Program Office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, morning rocket launches are partly responsible for the appearance of the lower-latitude clouds.
“Space traffic plays an important role in the formation and variation of these clouds,” says Michael Stevens of the Naval Research Laboratory, the lead author of a paper reporting the results in the journal Earth and Space Science. This is an important finding as scientists are trying to understand whether increases in noctilucent clouds are connected to climate change, human-related activities, or possibly both.
First documented in the late 1800s, noctilucent clouds are the highest clouds in our atmosphere. While rain clouds typically ascend no more than 10 miles (16 kilometers) above Earth’s surface, noctilucent clouds float some 50 miles (80 kilometers) high in a layer of the atmosphere called the mesosphere. (Because of this, they are also known as mesospheric clouds.) They shine at night because they’re so high up that sunlight can reach them even after the Sun has set for observers on the ground. These high-flying clouds form when water-ice crystals condense on particles of meteoritic smoke – tiny bits of debris from meteors that have burned up in our atmosphere.
Read more at NASA
Image: Noctilucent clouds appeared in the sky above Edmonton, Alberta, in Canada on July 2, 2011. (Credits: NASA/Dave Hughes)
