Lightning and thunder explanations in encyclopedias – from ancient Greece to Wikipedia

Abstract. After a brief introduction to encyclopedias, the explanation of lightning and thunder in well-known encyclopedias, from the works of Greek philosophers to encyclopedias of modern physics, is examined. Starting with Aristotle (who is not regarded as an encyclopedist but is very important for our topic), 10 out of more than 200 known encyclopedias are treated in some detail. This selection is certainly somewhat arbitrary, but it an attempt was made to choose encyclopedias which are highlights and which were widely circulated at their time. In antiquity and during the Middle Ages, the explanations of thunderstorms were generally quite different from the modern view, explaining, for instance, lightning as a consequence of thunder. Besides this, strange effects of lightning were often reported. Many authors of those times used the explanations of former encyclopedias, sometimes referring to earlier authors, often just plagiarizing. These ideas, unorthodox by our present understanding, persisted for almost 2 millennia in encyclopedias. From the middle of the 18th century onward, physical explanations began to emerge; these are still valid today. More and more correct details regarding lightning and thunder and the results of experiments have been reported in encyclopedias. It is also attempted in this paper to name the insights of other scientists which the authors of contemporary encyclopedias do not mention but which should have been available at the time. Finally, it is stated that, even today, several details regarding thunderstorms are not well understood.