The set will feature real grass, an oak tree and "clouds" suspended from wires above the stadium - one of which will produce rain, provided the British weather does not provide its own on the night.

BBC: London 2012: Olympics opening ceremony details revealed

Nameless waterfalls tumble down from the plateau above, while the shadows of clouds dance across treeless slopes.

BBC: An Icelandic journey to the centre of the earth

It was colder than ever now, but the sky had cleared, and a bright moon had emerged from the clouds, cold and white in a pool of indigo sky right above the garden.

NEWYORKER: The Cold Outside

So, those who manage the airspace above us go to great lengths to keep aircraft well away from the ash clouds that form during an eruption.

BBC: Flying through volcanic ash clouds