The magnificence of dawn breaking

As the sun rises over the remote settlement of Burketown in the Australian outback of northern Queensland, the first, pale rays of light illuminate an awesome sight.

It makes its first appearance as nothing more than a narrow, dark line on the horizon.

But as dawn breaks and it comes sweeping at high speed across the sky, its shadow rushing across the sandy ground and engulfing Burketown's few houses, the full majesty of this enormous cloud makes itself felt.

A huge, shimmering roll of white and grey, it blows in from the coast like an airborne glacier, hangs around 1,000ft above the ground, reaches perhaps a mile up towards the heavens, moves at up to 35mph and stretches up to 600 miles wide (about the same as the distance from Inverness to Exeter).

The meteorological phenomenon is known as the Morning Glory and usually occurs at first light in the months of September and October, drawing crowds of visitors, in particular gliders, hoping to catch it for an exhilarating and dangerous "cloud-surf".

Locals know it well enough to recognise the first signs that it might be on its way: a film of condensation on the clear doors of the beer fridges in the bar is a sign that the air is humid enough for the cloud to form.

Its arrival is preceded by a wind that whisks up the dust and dead leaves from the ground. But when it comes, the air falls suddenly still.

Gavin Pretor-Pinney, author of The Cloudspotter's Guide, made a trip halfway around the world simply to see the Morning Glory and calls it "the most amazing cloud in the world", and says he couldn't get over "the immensity of it, blocking out the moon and the Southern Cross as it passes".

The cause of this incredible natural phenomenon is not well understood, though it's thought to be linked to opposing sea-breeze currents that form over the Cape York peninsula to the north-east.

When these currents collide, the air rises upwards like a spine, and if the conditions - which are thought to include high humidity - are right, this eventually forms into the cylindrical Everest of clouds that astonishes all those who see it.