In the beginning, the Norse gods built a bridge from heaven to earth. They called it Bifrost, the shaking road. It was made of fire, water, grass and sunlight. It is normally invisible to us, only revealing itself when it rains and the sun shines. People then call it a rainbow. Heimdall, the great, white god, guards the bridge so that evil creatures cannot pass into heaven.

 In Iceland the sky is ever-changing. The prevailing south westerlies bring storm clouds that give way to rainbows. In spring and autumn, sunsets blaze across the sky. In summer, the sun hardly sets and in winter on a clear night the northern lights hang curtains of green and red across the sky (see Northern Lights for photos).

Cloud formations are many and varied, but in these northern latitudes, perhaps the most spectacular are nacreous and lenticular clouds. Lenticular clouds form high in the atmosphere, generally above mountains. Lens shaped, they have sometimes been mistaken for flying saucers.

Nacreous clouds form in the stratosphere above polar regions. They can be seen just after sunset and before dawn, and are probably the most beautiful of all clouds with their shimmering mother-of-pearl iridescence. However, they have a dark side, as they play a part in the depletion of the ozone layer.

Images of atmospheric phenomena

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