Noctilucent clouds: Ethereal, night-shining clouds

Ripply, electric blue clouds in a deep blue sky above a lake just past sunset.
Noctilucent clouds seen over Alberta, Canada, last night (July 2-3, 2022) by @LadyBockBock on Twitter.

Heads up! is reporting that, toward the end of June 2022, NASA’s AIM spacecraft detected a sharp increase in the frequency of noctilucent clouds, aka night-shining clouds. It’s the most we’ve seen in 15 years, SpaceWeather said. Atmospheric physicist Cora Randall of the University of Colorado Boulder works with AIM data and prepared the plot below. She told

We’re speculating that the spike might be due to extra water vapor transported to higher latitudes from rocket launches. But much more quantitative analysis would be required to confirm that or not.

Tony Phillips, who writes, added:

The timing makes sense. It takes about 10 days for water vapor from rocket engines to waft up to the mesosphere. This takes us back to SpaceX’s launch of the Globalstar satellite on June 19, which caused a number of remarkable phenomena in the sky, due to the extra burn time of its 2nd-stage engine. Noctilucent clouds may be yet another byproduct of that unusual launch.

Noctilucent clouds are normally a polar phenomenon. However, since the outburst began we have received reports of NLCs from as far south as Washington State and Oregon. Look for the clouds, ripply and electric-blue, just after sunset.

Keep tabs on noctilucent clouds via SpaceWeather’s RealTime gallery, or on Facebook via the group Noctilucent Clouds Around the World.

Graph with red line spiking upward much higher than a bunch of gray lines.
As June 2022 came to an end, NASA’s AIM spacecraft detected a sharp increase in the frequency of noctilucent clouds. “The most in 15 years,” scientists said. Image via Cora Randall/

What are noctilucent clouds?

Noctilucent clouds, or night-shining clouds, are thin clouds high up in Earth’s atmosphere – the mesosphere – as much as 50 miles (80 km) above Earth’s surface. Scientists think they’re made of ice crystals that form on fine dust particles from meteors. They can only form when temperatures are incredibly low and when there’s water available to form ice crystals.

So, why do these clouds – which require such cold temperatures – form in the summer? It’s because of the dynamics of the atmosphere. You actually get the coldest temperatures of the year near the poles in summer at that height in the mesosphere.

Rising air

Here’s how it works: during summer, air close to the ground heats up and rises. Since atmospheric pressure decreases with altitude, the rising air expands. When the air expands, it also cools down. This, along with other processes in the upper atmosphere, drives the air even higher causing it to cool even more. As a result, temperatures in the mesosphere can plunge to as low as -210 degrees Fahrenheit (-134 degrees C).

In the Northern Hemisphere, the mesosphere reaches these temperatures by mid-May in most years.

We see noctilucent clouds when most of the sky has grown dark. But the rays from the sun can still reach and reflect off these eerie, ethereal clouds. They have an electric-blue appearance. When satellites or astronauts view them from space, they go by the name of polar mesospheric clouds. If you want to see them for yourself, now’s the time to look!

Black space, shining ripply layer of clouds, dark orange narrow stripe above black silhouette of Earth.
Astronauts in the International Space Station (ISS) took this photo on January 5, 2013, when ISS was over the Pacific Ocean south of French Polynesia. Below the brightly lit noctilucent clouds, across the center of the image, the pale orange band is the stratosphere. Image via NASA.

It’s noctilucent cloud season

The season for noctilucent clouds at northerly latitudes is now. People at high latitudes report seeing noctilucent clouds. This happens every year, from about May through August in the Northern Hemisphere, and from November through February in the Southern Hemisphere.

In recent years, northern summertime noctilucent clouds have set records for low-latitude sightings. In 2019, for example, people observed them as far south as Las Vegas (+36N) and Los Angeles (+34N). Usually, though, they’re seen from higher latitudes.

Last year, 2021, was excellent for noctilucent clouds, with many sightings over the U.K. and comparable latitudes. said that the frequent sightings in 2021 were probably due to extra water in the mesosphere.

If you want to see how the noctilucent cloud season is going this year, you can check in on sightings at the excellent Facebook page Noctilucent Clouds Around the World. (Spoiler alert: You’ll see lots of recent reports and amazing pics!)

How to see these night-shining clouds

To see noctilucent clouds, you’ll want to have certain conditions in your favor. One factor is when to look. Right about now – mid-June to July – is typically when noctilucent clouds are most widespread.

You’ll also want to be positioned as far north as possible during the Northern Hemisphere’s peak season. Canada and the UK are two locations where you’ll have a better chance to spot night-shining clouds.

Then, look west about 30 minutes after sunset. The farther north you are, the longer throughout the night you can see them. That’s because the sun doesn’t dip as far below your horizon.

Noctilucent clouds look like electric, luminous tendrils of blue-white light. They are the clouds that glow after other clouds have darkened.

Diagram of light shining from the sun, bouncing off high clouds to a location over the horizon.
When the sun is below the horizon but visible from the high altitude of noctilucent clouds, sunlight illuminates these clouds. This causes them to glow in the dark night sky. Illustration via NASA.

What noctilucent clouds can teach us

Noctilucent clouds are sensitive to atmospheric temperatures. Therefore, they can act as a proxy for information about the wind circulation that causes these temperatures. First of all, they can tell scientists that the circulation exists. They can also tell us something about the strength of the circulation.

Scientists studying these clouds have included those from NASA’s Aeronomy of Ice in the Mesosphere (AIM) satellite. This satellite, launched in 2007, has observed noctilucent clouds using several onboard instruments to collect information such as temperature, atmospheric gases, ice crystal size and changes in the clouds. Also the amount of meteoric space dust that enters the atmosphere. You can find out what they are learning at NASA’s AIM page.

Studies have also shown that as the climate warms, noctilucent clouds become more visible.

Noctilucent clouds are like regular clouds in that they move in the sky. See the subtle movement of noctilucent clouds in the video below:

Noctilucent clouds from 2022

Blue sky with white clouds, below them, there is a house and some trees.
View at EarthSky Community Photos. | Joel Weatherly captured this image on June 20, 2022, in Edmonton, Alberta, Canada. He wrote: “One of my favourite sights in our short summer nights, noctilucent clouds were shining on the evening before our summer solstice.” Thank you, Joel!
Black silhouette of trees with wispy white clouds glowing, fading sunset and dark sky above.
View at EarthSky Community Photos. | Pam Yap in Edmonton, Canada, took this image of noctilucent clouds on June 1, 2022. Pam wrote: “First time capturing it. It was also the start of the season for us here in the Northern Hemisphere, so I was elated! I went to a nearby park on a clear night with my camera and tripod. I set it up and waited. It started appearing during the golden hours and stayed until the blue hours of sunset. This image I captured was the best out of the tons I took. It was magical to say the least!” Thank you, Pam!

Noctilucent clouds from Europe

A stand of tall trees in the foreground, with wispy blue night-shining clouds above.
View at EarthSky Community Photos. | Marek Nikodem captured these noctilucent clouds over Szubin, Poland, on June 24, 2021. Thank you, Marek!
Night-shining clouds over a cityscape, with a statue of a huge stone head in the foreground.
Karsten Russ in Nijmegen, Netherlands, caught these noctilucent clouds on the night of June 19, 2021. He posted this photo at the Facebook page Noctilucent Clouds Around the World and wrote that the statue is: “… a replica of a Roman mask which they found in the Waal river in Nijmegen. The original mask can be seen in a museum in Nijmegen.” Thank you, Karsten!
A panorama showing bright clouds at night, above the Eiffel Tower.
Noctilucent clouds seen over Paris, France, on June 18, 2021. Image via Loic Michel/ Notilucent Clouds Around the World.
Night-shining clouds above what looks like a city or town.
View at EarthSky Community Photos. | Rob de Graaf captured this image on June 18, 2021. He wrote: “Outbreak of noctilucent clouds above ‘s-Hertogenbosch, the Netherlands. Visible from about 10:45 p.m. until 12:20 a.m.” Thank you, Rob!
Night-shining clouds over a beach.
View at EarthSky Community Photos. | Kevan Hubbard at Seaton Carew, County Durham, England, caught these clouds in the early morning of June 20, 2021. He wrote: “A huge trailing noctilucent cloud and the southern end disturbed by gravity waves.” Thank you, Kevan!
Electric blue noctilucent clouds shining above a river with a lit-up stadium in the distance.
Katarzyna Kaczmarczyk captured these noctilucent clouds over Warsaw, Poland, at 1:30 a.m. on June 15, 2021. Thank you, Katarzyna!
Light-colored ripples in an otherwise dark sky.
View at EarthSky Community Photos. | Marek Nikodem near Szubin, Poland, took this image of noctilucent clouds on June 15, 2022. Marek wrote: “First noctilucent clouds in Poland this year.” Thank you, Marek!

Noctilucent clouds from around the world

Bright clouds, shining at night, reflecting in a pool.
View at EarthSky Community Photos. | Harlan Thomas captured this image on June 17, 2021. He was about 20 miles (30 km) north of Calgary, Alberta, Canada. He wrote that this image consists of 7 stitched images and said: “This was simply an amazing morning where the noctilucent clouds poured over the zenith into the southern skies, truly a beautiful sight to behold.” Thank you, Harlan!
Light clouds streak across a dark blue scene with a river below and mountain silhouettes that divide the water from the sky.
Doris Guevara de Isert caught these noctilucent clouds at the Powell River, British Columbia, Canada, on June 16, 2021. Image via Noctilucent Clouds Around the World.
Dark horizon, orange to blue sky with whitish wispy clouds.
View at EarthSky Community Photos. | Ben King in Israel captured this photo of noctilucent clouds on June 22, 2021. He wrote: “On my way to work, it’s usually dark, but these bright clouds above the horizon caught my eye. In disbelief, I thought they couldn’t possibly be noctilucent clouds. But they couldn’t really be anything else. I read many reports that there were record amounts of these clouds being seen at higher latitudes.” Thank you, Ben! Seeing noctilucent clouds at such a southerly location is rare. Ben didn’t say where he was in Israel, but the latitude of the northern edge of that country is about 33 degrees north.

Share your noctilucent cloud photos with EarthSky

Bottom line: As of late June 2022, the AIM satellite is reporting an increase in the frequency of noctilucent clouds … “most in 15 years!” Possibly due to a SpaceX launch in mid-June.

Visit SpaceWeather’s RealTime Noctilucent Cloud Gallery

Visit the Facebook page Noctilucent Clouds Around the World

July 3, 2022

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