In the summer and winter of 1783-1784 a large part of the northern hemisphere from 35o N to the north pole experienced unusual and extreme weather and atmospheric phenomena. In particular, Europe was shrouded by a persistent and widespread dry fog or haze. This fog led to a significant reduction in sunlight, a red or pink Sun at sunrise and sunset, and occasionally a blueish-green Sun. The haze arrived in western Europe around the middle of June but by the end of June virtually all of Europe was covered. During the same period there was also acid rain that caused damage to vegetation. The French naturalist M. Mourgue was the first of several people to correctly link the dry fog to the Laki fissure eruption in Iceland. Among the others was Benjamin Frankln who was ambassabor to France at the time. He gave the following description of the fog during a presentation in 1784:

"During several of the summer months of the year 1783, when the effect of the sun's rays to heat the earth in these northern regions should have been greater, there existed a constant fog over all Europe, and a great part of North America. This fog was of a permanent nature; it was dry, and the rays of the sun seemed to have little effect towards dissipating it, as they easily do a moist fog, arising from water. They were indeed rendered so faint in passing through it, that when collected in the focus of a burning glass they would scarce kindle brown paper. Of course, their summer effect in heating the Earth was exceedingly diminished. Hence the surface was early frozen. Hence the first snows remained on it unmelted, and received continual additions. Hence the air was more chilled, and the winds more severely cold. Hence perhaps the winter of 1783-4 was more severe than any that had happened for many years."

Benjamin Franklin, US Ambassador to France 1776-1785
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Dry Fog Impacts:
    1. People in Europe complained of headaches, respiratory problems and asthma attacks.
    2. Unusually cold in Russia, Siberia, China and Japan.
    3. 1783/1784 was the most severe winter in Europe and North America during the last 250 years.
  Area impacted by the dry fog of 1783. Dates indicate first arrival of fog.