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Summer skies bring striking cloud displays

Cecilia Daly
BBC News NI weather presenter
Happy Snapper A denim blue sky is lit up by silvery wisps of cloud. The sun is breaking through below the lower clouds and casting a faint golden light.Happy Snapper
This dramatic formation was captured in Limavady, County Londonderry, on Monday

Striking displays of clouds which are mostly only seen in the summer months have been appearing in the skies over Northern Ireland in recent nights.

Noctilucent clouds occur at extremely high levels in what is known as the mesosphere - a layer in the atmosphere above where our regular clouds and weather systems live, about 76-85km high - on the edge of space.

The clouds require very low temperatures in this part of the upper atmosphere, which only happen in the summer months, to allow water vapor to freeze into ice crystals.

These ice crystals then need to condense onto dust particles, which can originate from meteors or even volcanic eruptions.

Alistair Hamill A blue sky is scattered with lilac and lavender toned clouds. It sits above a body of water with golden city lights twinkling in the background. Alistair Hamill
The rare cloud formation could be seen in Portrush, County Antrim, on Sunday

Noctilucent clouds, also known as night-shining clouds, become visible when the sunlight, even though the sun is below the horizon, illuminates them from below, creating a shimmering effect.

According to the Met Office, the best time to see noctilucent clouds is on clear nights between late May and mid-August, about 90 to 120 minutes after sunset or before sunrise.

Sightings are most common during June and July.

Paul J McFarland An aerial view of a city is cast mostly in darkness but is faintly illuminated by street lights and a slight strip of sun in the distance. There is a patch of scattered clouds in the sky. Paul J McFarland
Ralph Smyth A denim blue sky is lit up by streaks of light clouds. There is a dark silhouette of a tree and the roofs of houses below. Ralph Smyth
Noctilucent clouds lit up the sky over Lisburn
The twilight show as seen from Newry on Sunday night