Funny blue clouds light up the Arctic sky

In this NASA photo you can see what “noctilucent” clouds, 80 km above the Earth’s surface, look like.

This NASA satellite image shows the location of the high-level blue clouds on May 19, over northern Russia.

Here’s something you won’t see from the ground: a luminous patch of blue drifting across the Arctic.

But a satelliete operated by the National Aeronautic and Space Administrations, called “Aeronomy of Ice in the Mesosphere,” recently spotted the shiny blue cloud drifting across the Arctic Circle.

The sighting marked the beginning of the 2015 season for what’s called “noctilucent” or night-glowing clouds, NASA said in a recent news release.

The first clouds appeared May 19, a bit earlier than researchers expected — and by now these short-lived clouds have gone.

But they’re special, because these clouds are the Earth’s highest, floating 80 kilometres above surface.

In the past, the clouds were considered to be a polar phenomenon, confined mainly to the Arctic.

But in recent years they have spread, with sightings as far south as Utah and Colorado in the western United States.

And this could be a sign of increasing greenhouse gases in Earth’s atmosphere, NASA said.

That’s because the clouds are very cold and filled with tiny ice crystals, which glow blue when the sun hits them.

Sky-watchers first noted these clouds in 1885 about two years after the eruption of Krakatoa volcano in Indonesia. While Krakatoa’s ash settled and the sunsets faded, the blue clouds didn’t go away.