A summer rarity: the clouds observed only at specific locations and specific times.

What are Noctilucent Clouds?

At twilight, silvery streaks stretch across the sky, illuminated by the Sun below the horizon. Noctilucent clouds are very high altitude clouds, most commonly sighted from mid latitudes in the Northern Hemisphere during the summer months, before sunrise or after sunset. These are particles of ice and dust in the Mesosphere, some of which may have originated from outer space!

Appearance

These clouds appear as silver-blue streaks above where the Sun will rise or has set. It may seem like the dark sky is fractured. They are illuminated by the Sun from underneath, so may be visible when the sky is still yellow, as seen below.

^ The illuminated clouds (Credits: Olesya Rtveliashvili)

When to Observe

Noctilucent clouds are best observed in the Northern Hemisphere during the summer months of June and July. They are seen in countries such as the UK, Denmark and Norway at dusk or dawn. This makes them impossible to be seen beyond the Arctic/Antarctic Circle where the Sun doesn’t appear to rise or set. The small window when observation is possible makes sightings rare.

How to Photograph

The best time to photograph Noctilucent clouds is at twilight, where the location and time meets the criteria mentioned above. For latitudes around 55°N, I recommend to photograph around the Summer Solstice close to midnight. Look towards the NW sky at times closer to sunset, where the clouds are still illuminated by the Sun from underneath. For times closer to sunrise, look towards the NE sky. Noctilucent clouds don’t always appear in the sky so this may take a few tries.

My decision to photograph the clouds was spontaneous; it was midnight and my aim was to capture the stars instead. However, it was twilight and in the Northern sky, a yellow glow illuminated them. It was my first ever time seeing the clouds. I set up my DSLR and tripod and used an exposure time of 0.5s and ISO 4000 to capture the image above.