by Javier Vinós & Andy May
“Probably no subfield of meteorology has had as much effort devoted to it as the effects of solar variability on weather and climate. And none has had as little to show for the research labor.” Helmut E. Landsberg (1982)
1.1 Introduction
The sun has been correctly identified as the source of climate since the dawn of human intelligence, and consequently the sun was worshipped in many ancient cultures. Large sunspots are visible with the naked eye when the sun is low on the horizon and partially obscured by dust or smoke. Several myths and iconography suggest sunspots were known to ancient cultures from America, Africa, and Asia, however, the first written mention of a sunspot comes from Theophrastus’ De Signis Tespestatum c. 325 BC. This first written record of solar variability was already linked to a climatic effect, since Theophrastus mentions it is related to rainfall. Theophrastus is considered the father of botany and was a student of Aristotle. He succeeded Aristotle as the head of the Lyceum when Aristotle, teacher of Alexander the Great, had to flee Athens due to anti-Macedonian sentiment. Theophrastus’ mention in passing of sunspots must have referred to common knowledge from the past, since he lived during the Greek grand solar minimum of 390–310 BC (Usoskin 2017) and it is very unlikely that anybody at that time could have seen a sunspot with their naked eyes. Most naked-eye sunspot observations known to us come from China, where records have been found starting from 165 BC. The oldest known drawing of actual sunspots is from the Chronicon ex chronicis by John of Worcester, dated in the manuscript to December 1128, during the Medieval grand maximum in solar activity.
Continue reading “The Sun-Climate Effect: The Winter Gatekeeper Hypothesis (I). The search for a solar signal”