4. American and British scientists observed the growing cloud in 1816, but did not know what it was.
In April, 1816, Congress adjourned after what it considered to have been a productive spring session (they voted themselves a pay raise as one of their final acts) just as American astronomers noted a growing dark spot which appeared to be on the surface of the sun. The British noticed it too, as well as other spots, which famed astronomer Sir Frederick William Herschel attributed to gaseous disruptions beneath the sun’s surface. Scientists on both sides of the Atlantic noted that as the spots on the face of the sun spread, the brightness visible on earth seemed to fade. The observations coincided with what was becoming, across the United States and Europe, an abnormally cold and dry spring in many places, abnormally cold and wet in others, but consistently across the northern hemisphere, abnormally cold. This phenomena was occurring in the aftermath of what had been an unusually mild and dry winter, especially in New England, a region not known for mild winters.
As winter gradually eased into spring, the weather in the United States became, to the casual observer, fickle, a mood no stranger to March and April. Fruit trees in Richmond, Virginia, were no doubt beautiful that spring when icicles formed overnight on their blossoms. Then, as Jefferson noted, the spring in Virginia became unusually dry. By that time the fruit crop for the year, cherries, grapes, berries, apples, peaches, apricots, plums, all were inexorably damaged by the killing frost, and in many cases fruit trees themselves were threatened. In the unusually dry soil, plows broke earth not yet ready to receive new seed or seedlings, and what was planted received insufficient water to grow. Virginia in 1816 was embroiled in debate (among farmers) over climate change. Jefferson had argued that the climate had been changing for three decades, using the data he had recorded in his Farm Books. Others, less scientifically minded, began to suspect divine intercession in the affairs of men.