Earth’s rarest clouds were sighted by skygazers in parts of the western US, Europe and Canada over the weekend, a vivid spectacle not seen for about 15 years.
Known as noctilucent, these clouds glowed a stunning blue in the sky just after the sun dipped below the horizon.
Reports of the eerie-looking clouds have come from Oregon, Washington, Alberta, the UK and Denmark.
Noctilucent clouds (NLCs) form in the mesosphere, which sits at an altitude of about 50 miles — making it the highest in Earth’s atmosphere.
The clouds are made up of ice crystals that become visible at dusk when the sun shines over the horizon.
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Earth’s rarest clouds were sighted by skygazers in parts of the western US, Europe and Canada over the weekend, and it’s the first time they’ve been seen in about 15 years. Pictured are the clouds over London
“There really is nothing quite like it,” the Seattle office of the National Weather Service wrote on social media, noting that these are the “most vivid displays of noctilucent clouds” seen in the region in decades.
The clouds typically form in late spring and early summer as the lower atmosphere warms.
Atmospheric circulation pushes air upwards, which then expands and cools.
Water vapor becomes trapped in the clouds, freezes into ice crystals, and forms meteorite dust.
Known as noctilucent, these clouds glowed a stunning blue in the sky just after the sun dipped below the horizon. Reports of the eerie-looking clouds have come from Oregon, Washington, Alberta, the UK and Denmark (pictured).
Noctilucent clouds (NLCs) form in the mesosphere, which sits at an altitude of about 50 miles — making it the highest in Earth’s atmosphere. Picture shows Seattle, Washington
The clouds appear with electric blue and silver streaks and are typically seen 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 aboard the International Space Station have shared images of the phenomenon.
There is a belief that climate change is also contributing to their development and even that they are being seen at latitudes never seen before.
In 2019, for example, they were seen as far away as Joshua Tree, California, suggesting that with more greenhouse gases in the atmosphere, more water vapor is available for the glowing clouds to form.
Cora Randall, a professor at the University of Colorado Boulder, told the Washington Post that the increase in clouds could be due to excess water vapor in the atmosphere from rocket launches.
Another study suggests that the occurrence of NLCs varies from year to year and even 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, which gave a 12th-century church an eerie glow.
Ollie Taylor, an astrophotographer, photographed “noctilucent” clouds that lit up the night sky of southwest England with spectacular blue and silver streaks.
The clouds appear with electric blue and silver streaks and are typically seen at latitudes of 45 and 80 degrees in the northern and southern hemispheres. Pictured is Alberta, Canada
On June 22, Taylor set out to capture the noctilucent clouds in Dorset, on the south coast of England.
He arrived at Knowlton Church amidst a Neolithic monument and began photographing the scene from 2am to 2:50am.
“It was an excellent night of shooting when we arrived on location in the evening and were already greeted by glowing noctilucent clouds that were better than I had seen in southern England before,” said Taylor.
“The electric blue complemented the misty landscape and eerie structure.”
According to the European Space Agency, Taylor tracked the clouds using a combination of sources, including space weather updates, webcam observations and a Facebook group.
In 2020, a photographer shared a stunning image of the phenomenon in the early hours of the morning, which gave a 12th-century church an eerie glow (pictured).
Noctilucent clouds were first described in the mid-19th century after the Krakatoa erupted.
Volcanic ash spread through the atmosphere, making for vivid sunsets around the world and provoking the first known observations by NLCs.
At first people thought they were a side effect of the volcano, but long after Krakatoa’s ash settled, the thin, glowing clouds lingered.