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isohel
isohel n. 
/ˈaɪsoʊˌhɛl/ [Greek ἥλιος sun] a line (imaginary or on a map) connecting points having the same amount or duration of sunshine.
Brit. /ˈʌɪsə(ʊ)hɛl/
, /ˈʌɪsə(ʊ)hɛl/U.S. /ˈaɪsəˌhɛl/
, /ˈaɪsəˌhɛl//ˈaɪsoʊˌhɛl/ΘΚΠ
the world > the earth > weather and the atmosphere > weather > study or science of weather > diagrams, graphs, or lines > [noun] > sunshine
isohel1904
1904 G. F. Goodchild & C. F. Tweney Technol. & Sci. Dict. 323/1 Isohels, lines connecting places having the same amount of sunshine.
1931 A. A. Miller Climatol. 22 The deviation of sunshine (shown on maps by lines of equal duration known as isohels).
1968 J. Gentilli Sun, Climate & Life (1971) xiii. 141/2 These lines are called iso-pleths as a general term, but..more specifically..isobars (equal pressure), isotherms (equal temperature),..isohels (equal sunshine),..etc.
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