Known as nocturnal clouds, these clouds glowed a stunning blue in the sky just after the sun moved below the horizon. Reports of the eerie clouds came from Oregon, Washington, Alberta, the United Kingdom and Denmark. Nocturnal clouds (NLCs) form in the mesosphere, which is at altitudes of about 50 miles – making them the highest in Earth’s atmosphere. The clouds are made up of ice crystals that become visible during twilight when the sun shines from the horizon. Scroll down for videos The rarest clouds on Earth were spotted by skywatchers in parts of the western US, Europe and Canada over the weekend, and it’s the first time they’ve been seen in 15 years. In the photo are the clouds over London “There’s nothing else like this,” the National Weather Service office in Seattle wrote on social media, noting that it was the “most vivid nighttime cloud display” seen in decades in the region. Clouds usually form in late spring and early summer when the lower atmosphere becomes warmer. Atmospheric circulation pushes air upward, which then expands and cools. Water vapor gets trapped in clouds, freezes into ice crystals and forms meteor dust. Known as nocturnal clouds, these clouds glowed a stunning blue in the sky just after the sun moved below the horizon. Reports of the eerie clouds came from Oregon, Washington, Alberta, the UK and Denmark (pictured) Nocturnal clouds (NLCs) form in the mesosphere, which is at altitudes of about 50 miles – making them the highest in Earth’s atmosphere. Photo shows Seattle, Washington The clouds appear streaked with electric blue and silver and are usually found at latitudes of 45 and 80 degrees in the northern and southern hemispheres. And the stunning display can even be seen from space, as astronauts on the International Space Station share photos of the phenomenon. There is some belief that climate change is also contributing to their growth, even making them appear in never-before-seen latitudes. For example, in 2019, they were seen as far south as Joshua Tree, California, suggesting that with more greenhouse gases in the atmosphere, there is more water vapor available to form the glowing clouds. Cora Randall, a professor at the University of Colorado Boulder, told the Washington Post that the increase in clouds may be due to excess water vapor in the atmosphere from missile launches. Another study suggests that the appearance of NLCs varies from year to year and even from decade to decade, but that overall, they have become “significantly” more visible. In 2020, a photographer shared a stunning image of the phenomenon in the early hours of the morning that gave a 12th century church a fantastic glow. Ollie Taylor, an astrophotographer, snapped ‘nocturnal’ clouds that lit up the night sky in south-west England with striking streaks of blue and silver. The clouds appear streaked with electric blue and silver and are usually found at latitudes of 45 and 80 degrees in the northern and southern hemispheres. Pictured is Alberta, Canada On June 22, Taylor set out on an expedition to capture the nocturnal clouds in Dorset, which is on the south coast of England. He arrived at Knowlton Church in the middle of a Neolithic monument and began shooting the scene starting at 2am until 2:50am. “It was a great night of filming, arriving on location in the evening and already being greeted with night clouds better than I’ve seen before in the south of England,” Taylor said. “The electric blue complemented the misty landscape and eerie structure.” Taylor tracked the clouds using a combination of different sources, including space weather updates, webcam observations and a Facebook group, according to the European Space Agency. In 2020, a photographer shared a stunning image of the phenomenon in the early hours of the morning that gave a 12th-century church a ghostly glow (image) Nocturnal clouds were first described in the mid-19th century after the eruption of Krakatau. Volcanic ash spread into the atmosphere, creating intense sunsets around the world and causing the first known observations of NLCs. At first people thought it was a side effect of the volcano, but long after Krakatau’s ash had settled, the pointy, glowing clouds remained.
WHAT ARE NIGHT CLOUDS (NIGHT LIGHTS)?
Nocturnal clouds, also called polar mesospheric clouds, form between 47-53 miles above the Earth’s surface (76-85 km), according to NASA. Here, water vapor freezes into clouds of ice crystals, which are illuminated when the sun is below the horizon. They are sown by debris from decaying meteorites, giving them a “shocking” blue hue when they reflect sunlight. Clouds form during the summer of both the northern and southern hemispheres.
