Meteorology

Meteorology (Greek Μετεωρολογικά, Latin Meteorologica) is a treatise by Aristotle that systematically sets out what he took to be the features common to air and water, along with the kinds of earth and the changes affecting its parts. Its date of composition is uncertain; it is usually placed around 340 BC, though no secure evidence exists. It is divided into four books: the first three deal with meteorological phenomena in a broad sense, while the fourth examines organic processes and the action of heat and cold on matter.

The starting point is the theory of the four elements (fire, air, water and earth), which combine in varying proportions to form all the materials of the terrestrial world. Aristotle understood them not as indivisible particles in the manner of Democritus's atoms, but as bearers of contrary qualities: hot, cold, dry and moist. On this basis he explains evaporation, dew and hoarfrost, rain, snow, hail, winds, rivers, the erosion of coasts, earthquakes, thunder and lightning, comets, the Milky Way, the aurora borealis, and optical phenomena such as the rainbow and solar halos.

The work is historically important as the first comprehensive systematic treatise on meteorology. It discusses and sometimes corrects the views of earlier thinkers such as Anaxagoras, Democritus, the Pythagoreans and Empedocles. Its method combines observation with deductive reasoning guided by general principles, which at times leads him to read the phenomena so that they fit the theory. It also presents a picture of a spherical universe in which earth, water and atmosphere are arranged in layers.

Its influence was considerable. An Arabic compendium attributed to Yahya ibn al-Bitriq circulated among Muslim scholars and, translated into Latin by Gerard of Cremona in the twelfth century, reached Western Europe. Later, William of Moerbeke's translation was widely read and commented on by Thomas Aquinas, and the work was often printed during the Renaissance. Its explanations shaped Western meteorology until the seventeenth century.