Weird Weather

What they had seen were 'sundogs', created by microscopic ice crystals in high wispy cirrus clouds, bending sunlight like glass prisms so that a pair of 'ghost' images of the sun appeared alongside the real sun. It's more common than you'd think - watch out for a veil of cirrus cloud over the sun on a bright day. Small wonder that these sorts of optical phenomena can easily be taken as religious signs. One memorable case was the tragic mountaineering expedition led by Edward Whymper on the first ascent of the Matterhorn in 1865. They mountaineers reached the peak but on their descent tragedy struck when four of the men fell down a precipice to their deaths. Later that evening Whymper saw an amazing vision: a circle of light with three crosses in the sky. "The ghostly apparitions of light hung motionless; it was a strange and awesome sight, unique to me and indescribably imposing at such a moment." Whymper had seen sunlight split by a veil of thin cloud into a large bow, part of a horizontal circle with vertical pillars of light crossing it. A similar sort of horizontal band can also be seen when you look at a light through a window smeared with grease in one direction or reflected by finely ribbed glass; the band of light is always seen at right angles to the ripples. Mountaineers also see ghosts! Huge shadowy spectres called Brocken Spectres, after the Brocken peak in Germany, are created by the shadows of mountaineers projected onto low clouds and reflected back by the tiny water droplets in the mist. Probably the commonest light show in the sky are mirages. They can bend light over the horizon so that people as far as Hastings have clearly seen the French coast across the English Channel, and sailors in Dublin Bay have claimed to see Mount Snowdon a 100 miles away.

These mirages are created by calm, warm air sitting on top of cold air - a temperature inversion - bending light from over the horizon like a glass prism, creating amazing images and revealing places hidden over the horizon. On rare occasions a temperature inversion turns into an even weirder light show. In 1957 passengers on the cruiser Edinburgh Castle sailing up the English Channel saw a line of ships upside down on the horizon - but they were upside down, some on top of each other, funnel to funnel and elongated. The images were ships projected from below the skyline. With this sort of optical trickery it's not surprising that mirages can explain quite a few UFO sightings. Long before flying saucers were ever heard of, sailors reported seeing ships sailing in the sky. This might explain the legend of the Flying Dutchman, a ghostly ship that haunted the seas around South Africa's Cape of Good Hope in stormy weather, luring ships to their destruction.