April 17th, 2010
The Laki Fissure
The 2010 Eyjafjallajökull eruption has ruined travel plans but does not rank as particularly disastrous, except financially for the air companies. A volcanic eruption in Iceland in 1783 – the Laki Fissure eruption – was catastrophic for the Icelanders (25% of the population died in the ensuing famine) and had serious consequences in Britain.
The amount of volcanic ash in the atmosphere over the UK gave rise to the “sand-summer”, as the 1783 summer became known. The amount of sulphur dioxide released by the eruption was colossal – 120 million tons:
approximately equivalent to three times the total annual European industrial output in 2006, and also equivalent to a Mount Pinatubo-1991 eruption every three days – Wikipedia
The resulting smog – the Laki Haze – was deadly, killing as it spread over western Europe. It reached Great Britain by late June of 1783, and thousands died from sulphur dioxide poisoning, outdoor workers being particularly vulnerable.
The effect on the weather was no less dramatic. As the haze heated up, a serious of heavy thunderstorms were unleashed, hailstones causing livestock losses. Gilbert White described that summer in The Natural History of Selborne: Read the rest of this entry
April 17th, 2010
One of the effects of volcanic ash in the atmosphere is to scatter light. When only longer light waves reach the earth, the blood-red sunsets associated with volcanic explosions are observed.
More unusually, if the particles suspended in the atmosphere are all of a particular size, rather than a mixture, the sun and moon can turn blue. This phenomenon was seen in Britain when Krakatoa erupted in 1883:
Clouds of dust hung suspended in the stratosphere for months, causing strange after-effects. All over the world, the most beautiful sunsets were witnessed. In Paris, New York, London, and Cairo, the setting sun appeared blue, leaden, green and copper-coloured. At night, the moon and stars appeared green. – August 1963 issue of Popular Science
September 18th, 2009
photo taken near Dundee by John Gilmour as featured in AuroraWatch
Of course the best viewing place is in the Arctic Circle, but the Northern Lights are occasionally visible from Britain. On rare occasions they are visible as far south as the Mediterranean.
Lancaster University’s AuroraWatch has a gallery of images that testify to the visibility of the Aurora in places like Folkestone and Staffordshire. The photographs show awe-inspiring displays of green and red light rampaging above the roof tops and television aerials. Read the rest of this entry