Climata

The climata (singular clima) were the ancient divisions of the inhabited portion of the spherical Earth by parallel circles centered on the Pole.[1] The word stems from the Greek κλίμα, Latin clima, terms which are originally geometric in nature, κλίμα meaning inclination or slope of the ground.[2]

Historical Development

The climata were defined by the length of the longest daylight, and were further associated with specific geographical locations. There were seven classical climata, although in his Almagest Ptolemy gave a more extensive listing of 39 climata, from which the following excerpt is tabulated:[3]

Clima Longest Daylight Location Latitude
12 hours Equator 0°
I 13 hours Meroe 16°27'
II 13½ hours Syene 23°51'
III 14 hours Lower Egypt 30°22
IV 14½ hours Rhodes 36°
V 15 hours Hellespont 40°56'
VI 15½ hours Mid-Pontus 45°1'
VII 16 hours Mouth of Borysthenes 48°32'
17 hours Mouth of Tanais 54°1'
18 hours South of Little-Britain 58°
19 hours North of Little-Britain 61°
20 hours Thule 63°
21 hours Unknown Skythians 64°30'
22 hours 65°30'
23 hours 66°
24 hours 66°8'40"
2 months 69°30'
4 months 78°20'
6 months North Pole 90°

In Medieval Europe, the climates for 15 and 18 hours were used to calculate the changing length of daylight through the year.[4]

References

  1. ^ Otto Neugebauer, A History of Ancient Mathematical Astronomy, (New York: Springer Verlag, 1975), p. 725. ISBN 0-387-06995-X
  2. ^ H. G. Liddell and R. Scott, A Greek English Lexicon.
  3. ^ Otto Neugebauer, A History of Ancient Mathematical Astronomy, (New York: Springer Verlag, 1975), pp.43-5. ISBN 0-387-06995-X
  4. ^ Otto Neugebauer, A History of Ancient Mathematical Astronomy, (New York: Springer Verlag, 1975), p. 731. ISBN 0-387-06995-X