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Noctilucent clouds: The season starts now!

Noctilucent cloud season has begun! Normally, in late May or June, people at higher latitudes on the globe begin reporting these ethereal, electric-blue clouds after nightfall. The first batch of reports began this year on June 4, 2023. See the first night-shining clouds of the season below.

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. In fact, you actually get the coldest temperatures of the year near the poles in summer at that height in the mesosphere.

Blue sky with wispy white clouds reflecting in a lake. Orange horizon.
Photo of noctilucent clouds taken in Laboe, Germany, on June 21, 2019. Image by Matthias Süßen/ Wikipedia/ CC BY-SA 4.0.

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. But, 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 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. Indeed, 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 the 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.

Where to watch for noctilucent clouds

As with the aurora, it helps to be closer to the poles to see this phenomenon. You can keep tabs on noctilucent clouds via SpaceWeather’s RealTime gallery, or on Facebook via the group Noctilucent Clouds Around the World.

Dark blue sky with bright clouds over a town covered in trees and some houses.
EZ Lorenz Imagery took this photo on June 25, 2023, in Bellevue, Washington, and wrote: “Finally! The NLCs are baaack! (47.61° N). In spite of the light pollution, some cloud cover and the bright moon they were beautifully visible to the unaided eye from downtown Bellevue, Washington state, USA, just minutes from Seattle. About 10:40 pm local time, 90 minutes after sunset to the NW.” Thank you! See more stunning images from this amazing photographer here.

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.

Field of pink and purple flower spikes, an orange horizon and glowing wispy clouds in a dark sky above.
View larger. | Jakob Arthur Andersen from Storstrom, Denmark, shared this image of noctilucent clouds on June 6, 2023. Thank you, Jakob! You can click here to see more amazing photos at his website and here to see Jakob’s photos at Instagram.

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 – 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 U.K. are two locations where you’ll have a better chance to spot night-shining clouds. (However, rocket launches can inject particles into the upper atmosphere and make noctilucent clouds visible to areas that aren’t so far north.)

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: location of sun below horizon from observer's point of view and sunlight striking clouds high above.
Noctilucent clouds are night-shining clouds because they are so high up that after the other clouds are dark, the sun can still reach them. These polar mesospheric clouds appear as eerily blue in a mostly darkened sky. Chart via John Jardine Goss/ EarthSky.

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 gotten help 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. It even accounts for 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 from 2023

Do you have images of the 2023 noctilucent clouds to share? We’d love to see them! Submit them to EarthSky Community Photos.

Big rocks creating a circle. Orange horizon, blus sky and bright clouds.
Nick Bull from Amesbury, England, took this photo on June 25, 2023, and wrote: “Noctilucent clouds over Stonehenge last night. Finally, after a lot of sitting around waiting over the last 4 weeks, I got my chance to capture them at Stonehenge around 23.00. Noctilucent clouds are extremely rare very high clouds seen in the night sky, usually on clear, summer nights. They become visible about the same time as the brightest stars and are usually bluish or silvery.” Thank you, Nick!
Lake with trees and light of houses at the background. There is a lake reflecting bright lights on a pink and dark blue sky.
View at EarthSky Community Photos. | Noel Bowman in Kent, Washington, took this photo of noctilucent clouds on June 25, 2023. Noel wrote: “Shot at Lake Meridian after sunset. The noctilucent clouds seemed to last from 10:30pm till 11:40pm. Fairly wide display as well.” Thank you, Noel!
Noctilucent clouds: Foreground of car with headlight shining, background of thin, wispy light-blue clouds in darkening sky.
View at EarthSky Community Photos. | Villiam Hansen in Bornholm, Denmark, captured this image of noctilucent clouds on June 4, 2023. Villiam wrote: “Noctilucent clouds started last night while watching the moonrise in the other direction. I noticed a small bit of dust on the lens and tried to blow it away with my mouth. That gave the fog effect on the lights, and I kind of like it. Over the car we see clouds that light up in the darkness.” Thank you, Villiam!

Noctilucent clouds from 2022

Wispy, glowing white clouds in dark sky over a black horizon with a dim sunset along it.
View at EarthSky Community Photos. | Kris Hazelbaker in Grangeville, Idaho, took this photo of noctilucent clouds on July 16, 2022, and wrote: “I happened to look outside around 3 a.m., and noticed a glow in the northern sky. Thinking it was an unexpected northern lights display, I walked outside to get a better look. Instead of an aurora, these noctilucent clouds were glowing in the northern sky, as Venus was rising in the northeast.” Thank you, Kris!
Darkening blue sky with white ripply clouds, below them, there is a house with a weathervane on top 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 favorite sights in our short summer nights, noctilucent clouds were shining on the evening before our summer solstice.” Thank you, Joel!
Black silhouette of evergreen trees with glowing, wispy white clouds, 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!

Bottom line: The first noctilucent clouds of the 2023 season are here! Learn more about how to see them and submit your photographs here.

Visit SpaceWeather’s RealTime Noctilucent Cloud Gallery

Visit the Facebook page Noctilucent Clouds Around the World

Posted 
June 17, 2023
 in 
Earth

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