Theclimes (singularclime; alsoclima, pluralclimata, from Greek κλίμαklima, plural κλίματαklimata, meaning "inclination" or "slope"^[1]) in classicalGreco-Roman geography andastronomy were the divisions of theinhabited portion of thespherical Earth bygeographic latitude.^[2]

Starting withAristotle (Meteorology 2.5,362a32), the Earth was divided into five zones, assuming twofrigid climes (theArctic andAntarctic) around the poles, an uninhabitabletorrid clime near theequator, and twotemperate climes between the frigid and the torrid ones.^[3]Different lists of climata were in use inHellenistic andRoman time. ClaudiusPtolemy was the first ancient scientist known to have devised the so-called system of seven climes (Almagest 2.12) which, due to his authority, became one of the canonical elements of late antique, medieval European and Arab geography. InMedieval Europe, the climes for 15 and 18 hours of longest daylight at summersolstice were used to calculate the changing length of daylight through the year.^[4]

The modern concept ofclimate and the related termclime are derived from the historical concept ofclimata.

Ptolemy gives a list of parallels, starting with theequator, and proceeding north at intervals, chosen so that the longest day (summersolstice) increases in steps of a quarter of an hour from 12 hours at the equator to 18 hours at 58° N, and then, in larger steps, to 24 hours at theArctic Circle.

But for the purposes of his geographical tables, Ptolemy reduces this list to eleven parallels, dividing the area between the equator and 54°1' N into ten segments, at half-hour intervals reaching from 12 hours to 17 hours. Even later in his work, he reduces this to seven parallels, reaching from 16°27' N (13 hours) to 48°32' N (16 hours).

Ptolemy's system of seven climes was primarily adopted inArabo-Persian astronomy, by authors such asal-Biruni andal-Idrisi, and eventually byAmīn Rāzī, the author of the 16th-centuryhaft iqlīm (lit. 'seven climes'), while in Europe, Aristotle's system of five climes was more successful. This view dominated in medieval Europe, and existence and inhabitability of the Southern temperate zone, theantipodes, was a matter of dispute.^{[citation needed]}

To identify the parallels delineating his climes, Ptolemy gives a geographical location through which they pass. The following is a list of the 33 parallels between the equator and the polar circle (39 parallels between the equator and the pole)^[5] of the full system of climes; the reduced system of seven climes is indicated by additional numbers in brackets. Both Ptolemy's latitude estimates and modern values are provided. Ptolemy never considered theimpact of atmospheric refraction on his calculation of the length of the day. If you account for that and for the drift in orbital parameters since Ptolemy's time, his values are remarkably accurate, off by less than 30 arcseconds in most cases.

• Climate
• Four continents
• Geographical zone
• Roof of the World
• Seven Seas

• Berggren J.L., Jones A. (2000).Ptolemy's Geography: An Annotated Translation of the Theoretical Chapters. Princeton University Press. 216 p.
• Dicks D.R. (1955). "The ΚΛΙΜΑΤΑ in the Greek Geography".Classical Quarterly 5 (49): 248–255.
• Dicks D.R. (1956). "Strabo and the ΚΛΙΜΑΤΑ".Classical Quarterly 6 (50): 243–247.
• Dicks D.R. (1960)The Geographical Fragments of Hipparchus. London: Athlon Press. XI, 214 p.
• Diller A. (1934). "Geographical Latitudes in Eratosthenes, Hipparchus and Posidonius".Klio 27 (3): 258–269.
• Honigmann E. (1929).Die sieben Klimata und die πολεις επισημοι. Eine Untersuchung zur Geschichte der Geographie und Astrologie in Altertum und Mittelalter. Heidelberg: Carl Winter's Universitätsbuchhandlung. 247 S.
• The Itinerary of Alexander through the Seven Climes of Antiquity according to the Aljamiado-Morisco Rrekontamiento del rrey Alisandre. Santa Barbara, CA. Fifth Annual Middle East Studies Regional Conference. March 22, 2003.
• Kubitschek W. (1921). "Klima 2".Real-Encyclopädie der classischen Altertumswissenschaft. Ed. A. F. von Pauly, G. Wissowa et al. Stuttgart. Bd. XI.1: 838–844.
• Marcotte D. (1998). "La climatologie d'Ératosthène à Poséidonios: genèse d'une science humaine". G. Argoud, J.Y. Guillaumin (eds.).Sciences exactes et sciences appliquées à Alexandrie (IIIe siècle av J.C. – Ier ap J.C.). Saint Etienne: Publications de l'Université de Saint Etienne: 263–277.
• Neugebauer O. (1975).A History of Ancient Mathematical Astronomy. Berlin, Heidelberg, New York: Springer Verlag: 43–45, 333–336, 725–733.
• Shcheglov D.A. (2004/2006). "Ptolemy's System of Seven Climata and Eratosthenes' Geography".Geographia Antiqua 13: 21–37.
• Shcheglov D.A. (2006): "Eratosthenes' Parallel of Rhodes and the History of the System of Climata".Klio 88: 351–359.
• Szabó Á. (1992).Das geozentrische Weltbild. Astronomie, Geographie und Mathematik der Griechen. München: Dt. TaschenbuchVerlag. 377 S.
• Szabó Á., Maula E. (1986).Les débuts de l'astronomie de la géographie et de la trigonométrie chez les grecs. Traduit par M. Federspiel. Paris: Libr. philos. J. Vrin. 238 p.

• Corbin, Henry (1977).Spiritual Body and Celestial Earth: From Mazdean Iran to Shi'ite Iran. Princeton University Press. pp. 17-50.

• Ancient Greek geography
• Climate and weather classification systems

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