© Met ÉireannNacreous or polar stratospheric clouds seen over Ireland this morning
Rare 'rainbow' clouds have been spotted across Ireland this morning.
The clouds have an iridescent or rainbow appearance and their presence is rare in Ireland.
The technical name for the eye-catching clouds are nacreous or polar stratospheric clouds.
They form high up in the stratosphere, between 15 and 25 kilometres high, over polar regions when the Sun is just below the horizon.
Nacreous clouds only form below -78 °C so are most likely to occur during the polar winter.
The ice particles that form nacreous clouds are much smaller than those that form common clouds, and it's these smaller particles that scatter light in a different way and create the distinctive iridescent appearance.
Due to their high altitude and the curvature of the Earth's surface, these clouds are lit up by sunlight from below the horizon and reflect it to the ground.
They are most likely to be viewed in places such as Scandinavia and northern Canada and because of this, they are often referred to as polar stratospheric clouds.
Due to the very low temperatures required, nacreous clouds are usually only visible from Ireland when the cold air which circulates around polar regions in the stratosphere is displaced and hovers temporarily over Ireland.
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