Before Parmenides and especially before Anaxagoras, there was no strong distinction between what we would call astronomy and what we would call meteorology. Both had to do with astra, stars or heavenly bodies, and with meteora, mid-air phenomena. On most theories, these were continuous with each other. Anaximander, it is true, had heavenly bodies that were much larger than earth but, my modern standards, not much larger: the sun consisted of a circular tube like a bicycle tire that had a diameter 27 times that of earth; the moon, a tube 18 earth diameters, and the stars orbits inside, perhaps 9 earth diameters. These tubes consisted of fire enclosed by air, so that they did not have great mass.[1] Anaximenes, slightly later, had some (lower) heavenly bodies flying like leaves around the circumference of the earth’s disk, blown by a kind of jet stream, while the stars were attached to the firmament or dome of heaven like nails, which revolved with the dome like a felt cap, he said.[2] Xenophanes saw the heavenly bodies as cloudlike structures whose fires were fed by vapors from the earth.[3] Heraclitus pictured the sun and moon as consisting of opaque bowls filled with fire.[4] Most thinkers seem to have viewed the heavenly bodies as fueled by evaporations.[5]
But if the heavenly bodies were constructed from earth and stone, as Anaxagoras held, then then they had to be held aloft by some kind of powerful centrifugal force, like that observed in twirling a ladle full of liquid, as Empedocles noted.[6] Breezes from the earth, even a strong circular jet stream, could not account for the motion nor, presumably, for their source of illumination. There had to be, according to Anaxagoras, a cosmic vortex that hurled the massive heavenly bodies at incredible speeds in enormous orbits. Either there was some sort of ring of fire high above the earth or there was some kind of friction that ignited the luminous heavenly bodies. (To be fair to Anaxagoras and his successors, the problem of heavenly fires would not be solved until the twentieth century, with the discovery of nuclear fusion in cores of stars at unimaginable pressures and temperatures.)
Furthermore, Parmenides’ theory of lunar light entailed that the sun (and moon) moved directly under the earth, rendering obsolete the theories, such as those of Anaximenes and Xenophanes, that confined the motion of the heavenly bodies to the space above the earth.
Early theories of weather did envisage vapors rising from the earth to account for clouds, winds, storms, precipitation of various sorts, lightning, rainbows, and the like. These theories tended to be like modern theories of the water cycle, except that the “chemistry” behind them was faulty and the details were speculative. Anaxagoras gave a basically correct account of the formation of hail in vertically-extended thunderclouds: water droplets rising to a great height freeze.[7]
Meteorological accounts tended to include a theory of earthquakes, which often involved the interaction between underground caverns and weather phenomena, including winds and rain. Oceanography also was treated along with the water cycle.
Early Greek natural philosophy gave rise to some specialized meteorological studies. For instance, the Nile floods in Egypt became a celebrated problem. For, unlike floods in Greece, which occurred when snow melted in the springtime, the Nile floods occurred in summer, with waters that flowed through vast stretches of the torrid Sahara Desert. How could they be accounted for? A number of natural philosophers proposed solutions, and the tourist/ historian Herodotus explored the Nile River with a desire to resolve the question. He rejected the myths of Egyptian priests and tested previous Greek theories against the evidence, offering his own thoughtful but complicated solution.[8] Modern research has established that the Nile is fed by melting snow from its distant sources in the southern hemisphere, but the floods actually result from annual monsoon rains falling in the Ethiopian highlands, resulting from weather patterns over the Indian Ocean.[9] Herodotus’ efforts, in any case, show the reach and influence of early Greek philosophy of nature. The very recognition of the problematic phenomenon in a far-off land shows the curiosity, sophistication, and scope of early Greek scientific studies.
[1] Anaximander A21, A22.
[2] Hippolytus 1.7.4-6 = A7; A14, A15.
[3] Xenophanes A38, A40, A41a, A43.
[4] Diogenes Laertius 9.1-11 = A1.
[5] Aristotle Meteorologica 354b33-355a8.
[6] Empedocles A67.
[7] Aristotle Meteorologica 384a14-20, b8-15 = A85+.
[8] Herodotus Histories 2.19-28; Graham 2003.
[9] Bonneau 1964.