How 18th-century weather diaries shed light on the effects of an Icelandic volcanic eruption on Scotland

On June 15 1783, Dr John Purcell went outside his house in Edinburgh, looked up at the clouds and wrote in his diary how dark and gloomy the sky was. The dark skies, he reported, continued for seven days followed by two or three days of fine weather. Then, on June 25 he began to describe the presence of a choking sulphurous haze that lingered over Edinburgh for the rest of the summer.