Wednesday, 4 February 2015

The Black Sun above Caverswall 1783

The residents of Caverswall were convinced on the 23rd June 1783 that the strange colour of the sun was down to supernatural causes. For a few days the sun was black which the more superstitious villagers blamed on the malevolent influence of the ghost of Lady Vane. It was also very hot and the fog was so thick that ships were unable to leave harbour. Not so far away from Caverswall ,the people of Derby witnessed an extraordinary thunderstorm and the blood red sun commenting on the state of the atmosphere.

What the observers in Caverswall, Derby and elsewhere were witnessing was the after effect of millions of tons of material being expelled far into the atmosphere by the eruption of an Iceland volcano Laki at the beginning of June. A large amount of sulphur dioxide was emitted, about three times the total annual European industrial output now  (but delivered to higher altitudes, hence  the more persistent).

 Iceland initially  suffered  grievously itself , about 20% of natives and 50 % of livestock either died from the effect of the gas or from the famine that followed. Further away outpourings of sulphur dioxide during  eruption  caused a thick haze to spread across Western Europe, The dense cloud of gases were blown south east. It reached Prague by the 17th. By the 20th it had arrived  in Paris and 3 days later it had crossed the Channel, A fine dust ,in effect, a volcanic ash  fell throughout England and the summer became known as the “Sand Summer”. It was a time of extremes as the very hot weather came with violent thunderstorms and hailstones which were so large that it was reported that Cattle were killed. The summer gave way to an early and long winter. The Naturalist Gilbert White recorded 28 days of frost in Hampshire, the River Severn froze at Worcester and cottages in Northamptonshire were covered so deeply with snow that the inhabitants starved to death. The deep snows and plunging temperatures killed thousands in Britain but it was the arrival of the gas the previous June that killed many more

 Inhaling the noxious gas causes victims to choke and their internal organs to swell as the gas reacts with the moisture in lungs and produces  sulphurous acid. In Great Britain, the records show that the additional deaths were among outdoor workers; the death rate in East Anglia was perhaps two or three times the normal rate. It has been estimated that 23,000 Britons died from the poisoning.

The meteorological impact of Laki continued, contributing significantly to several years of extreme weather in Europe.  In France, the sequence of extreme weather events caused poverty for the rural population, and a violent hailstorm in 1788 destroyed crops. These events contributed significantly to an increase in poverty that may in turn  have contributed to the French Revolution in 1789.

It would not have  been the first such occurrence to claim a dynasty in the 10th century the Eldgja eruption in Iceland caused  such freak weather conditions in China that the resultant famine bought down the Jin Dynasty.

Volcanoes in Iceland are  back in the news as scientists have been closely observing Iceland’s volcanic activity.  Bardarbunga volcano in the early autumn was continually spewing lava and sending tremors across the island. The amount of material voided is greater than a volcanic eruption of 2010 when ash and dust high in the altitude caused flights to be cancelled in the UK.