Meteorology (Aristotle)

Meteorology (Latin: Meteorologica or Meteora) is a treatise by Aristotle which contains his theories about the earth sciences. These include early accounts of water evaporation, weather phenomena, and earthquakes.

Physics

"...the motion of these latter bodies [of four] being of two kinds: either from the centre or to the centre." (339a14-15)

"So we must treat fire and earth and the elements like them as the material causes of the events in this world (meaning by material what is subject and is affected), but must assign causality in the sense of the originating principle of motion to the influence of the eternally moving bodies." (339a27-32)

This is a reference to the unmoved movers, a teleological explanation.

Four elements

"...four bodies are fire, air, water, earth." (339a15-16)

"Fire occupies the highest place among them all, earth the lowest, and two elements correspond to these in their relation to one another, air being nearest to fire, water to earth." (339a16-19)

"Fire, air, water, earth, we assert, originate from one another, and each of them exists potentially in each, as all things do that can be resolved into a common and ultimate substrate." (339a36-b2)

All terrestrial matter consist of these four elements. Various ratios of the elements combine to create the diverse materials found in nature.

Atmosphere

Water vapor

"Some of the vapour that is formed by day does not rise high because the ratio of the fire that is raising it to the water that is being raised is small." (347a13-15)

"Both dew and hoar-frost are found when the sky is clear and there is no wind. For the vapour could not be raised unless the sky were clear, and if a wind were blowing it could not condense." (347a26-28)

"...hoar-frost is not found on mountains contributes to prove that these phenomena occur because the vapour does not rise high. One reason for this is that it rises from hollow and watery places, so that the heat that is raising it, bearing as it were too heavy a burden cannot lift it to a great height but soon lets it fall again." (347a29-34)

Weather

"When there is a great quantity of exhalation and it is rare and is squeezed out in the cloud itself we get a thunderbolt." (371a17-19)

"So the whirlwind originates in the failure of an incipient hurricane to escape from its cloud: it is due to the resistance which generates the eddy, and it consists in the spiral which descends to the earth and drags with it the cloud which it cannot shake off. It moves things by its wind in the direction in which it is blowing in a straight line, and whirls round by its circular motion and forcibly snatches up whatever it meets." (371a9-15)

Aristotle describes the properties of tornadoes and lightning.

Geology

"So it is clear, since there will be no end to time and the world is eternal, that neither the Tanais nor the Nile has always been flowing, but that the region whence they flow was once dry: for their effect may be fulfilled, but time cannot. And this will be equally true of all other rivers. But if rivers come into existence and perish and the same parts of the earth were not always moist, the sea must needs change correspondingly. And if the sea is always advancing in one place and receding in another it is clear that the same parts of the whole earth are not always either sea or land, but that all this changes in course of time.. " (353a14-24)

Geography

"To judge from what is known from journeys by sea and land, the length [of the inhabited earth] is much greather than the width; indeed the distance from the pillars of Heracles [at Cadiz] to India exceeds that from Aethiopia [Sudan] to Lake Maeotis [Sea of Azov] and the farthest part of Scythia is the proportion of more than five to three" (362b19-23)

Hydrology

"The Red Sea, for instance, communicates but slightly with the ocean outside the straits,..." (354a1-3)

"The whole of the Mediterranean does actually flow. The direction of this flow is determined by the depth of the basins and by the number of rivers. Maeotis flows into Pontus and Pontus into the Aegean. After that the flow of the remaining seas is not so easy to observe." (354a11-14)

Spherical Earth

"The earth is surrounded by water, just as that is by the sphere of air, and that again by the sphere called that of fire." (354b23-25)

Aristotle is describing a spherical lithosphere (Earth), hydrosphere (water) and atmosphere (air and fire).

See also

• Bekker numbers
• Classical compass winds
• Timeline of meteorology
• History of science

External links

• Meteorology, translated by E. W. Webster (alternate @ mit.edu)
• Modern aspects of Aristotle's Meteorology