These are words many people use to describe one of the most beautiful screens in the sky: night clouds. And this is a good time for Canadians to try to see for themselves, especially this great weekend – if you have a clear sky. Every year, from about the beginning of June to August, these clouds – also known as NLCs or polar mesospheric clouds – make their appearance in the northern sky. They do not look like any of the most famous clouds: they look almost iridescent, bright and shining as either the darkness descends, the sun escapes and the stars begin to scatter in the sky or as the darkness begins to turn into daylight. as the sun begins to rise. Another image from the amazing show Noctilucent clouds this morning. Newcastle upon Tyne, United Kingdom. June 23, 2022. pic.twitter.com/FHWJlxnKs8 – @DavidBflower The phenomenon seems to have a typical formation formula: rising water vapor, very low temperatures and particles – such as dust left by meteorites in our atmosphere or even rocket exhaust – in which water vapor can freeze. NLCs are also incredibly high in the atmosphere, about 80 kilometers at an altitude. For comparison, the highest clouds we associate with the weather are at altitudes between five and 13 kilometers. Cloudy skies appeared over Medicine Hat, Alta., On June 26. (Submitted by Jackie Armstrong) It is also believed to be a somewhat new phenomenon. They were first reported in 1885, two years after the massive volcanic eruption of Krakatoa. Although the early belief was that it was due to the explosion and that they would disappear, they have seen it ever since.
How to see them
In the past, NLCs were observed mainly in the great northern latitudes, making Northern Canada an ideal location for observation. In recent years, however, they have been located further south, as far as Utah and even Nebraska in the United States. There is a belief that climate change is also contributing to their development, even to appearing in latitudes they have never seen before. For example, in 2019, they appeared south as the Joshua Tree, in California. The main theory is that with more greenhouse gases in the atmosphere, there is more water vapor in which they can form. A 2019 study suggests that the incidence of NLCs varies from year to year, even from decade to decade, but that overall, they have become “significantly” more visible. These glistening clouds appear during the summer in the northern hemisphere because more water molecules travel upward from the lower atmosphere and mix with meteorite debris. It is also a time when the mesosphere – where these clouds grow – is colder. CLOCKS Scientists have captured an impressive night sky image over Canada: Most of Canada is in a good position to see these inflated clouds, although those in southern Ontario may have more difficulty due to their lower latitudes. If you are going to try to locate them, the key is to have a good view of the northern horizon. You really do not need to get to a place with a dark sky in this case, as the clouds are bright, illuminated by the sun below the horizon. They most often occur about 30 minutes to two hours after sunset or 30 minutes to two hours before sunrise, as the sun should be about five to 13 degrees below the horizon. And you will be able to distinguish them from the weather clouds, as these clouds will be dark and not the bright NLC. So if you are in a cottage, a park or just out to celebrate this weekend, remember to look up. You never know what you will see.
