Clime - Ptolemy

Ptolemy

Ptolemy gives a list of parallels, starting with the equator, and proceeding north at intervals, chosen so that the longest day (summer solstice) 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 the arctic 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 by Arab and Persian authors such as al-Biruni, al-Idrisi and al-Razi, the author of the 16th century haft iqlīm (seven climes), while in Europe, Aristotle's system of five zones was more successful. This view dominated in medieval Europe, and existence and inhabitability of the Southern temperate zone, the antipodes, was a matter of dispute.

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 of the full system of climes, the reduced system of seven climes is indicated by additional numbers in brackets (note that the latitudes are the ones given by Ptolemy, not the modern exact values):

12:00 (equator)
12:15, 4°4' N: Taprobana (Sri Lanka)
12:30, 8°25' N: Avalite bay (Saylac, Somalia)
12:45 12°00' N: bay of Adulis (Eritrea)
(1.) 13:00, 16°27' N: Meroe island
13:15, 20°14' N: Napaton (Sudan)
(2.) 13:30, 23°51' N: Soene (Aswan)
13:45, 27°12' N: Thebes
(3.) 14:00, 30°22' N: Lower Egypt
14:15, 33°18' N: Phoenicia
(4.) 14:30, 36°00' N: Rhodes
14:45, 38°35' N: Smyrna
(5.) 15:00, 40°50' N: Hellespont
15:15, 43°04' N: Massalia (Marseilles)
(6.) 15:30, 45°01' N: the middle of the Black Sea
15:45, 46°51' N: Istros river
(7.) 16:00, 48°32' N: the mouths of Borysthenes (Dnepr)
16:15, 50°04' N: Maiotian lake
16:30, 51°06' N: the southern shore of Britannia
16:45, 52°50' N: mouths of the Rhine
17:00, 54°30' N: mouths of the Tanais river (Don)
17:15, 55° N: Brigantion in Britannia
17:30, 56° N: the middle of Great Britain
17:45, 57° N: Katouraktonion in Britannia
18:00, 58° N: the southern part of Britannia Minor
18:30, 59° N: the middle part of Britannia Minor
19:00, 61° N: the North of Britannia Minor
19:30, 62° N: Ebudes island
20:00, 63° N: Thule (Iceland)
21:00, 64° N: unknown "Scythian people"
22:00, 65° N
23:00, 66° N
24:00, 66°08'40'' N: the polar circle