| 释义 |
ubac, n. Geogr.
Brit. |ˈuːbak|, U.S. |ˈubæk|
[‹ French ubac (1907; originally French regional (south-eastern)) > adj.). Compare post-classical Latin ubacum (in an undated source in Du Cange), ubagum (1035), Catalan obac (839 as obago, 1371 as ubac), Middle French ubac situated in the shade (1505).]
A hillside or mountain slope which receives little sunshine, esp. (in the northern hemisphere) a north-facing one. Chiefly with reference to the Alps. Freq. attrib.
Contrasted with adret.
1922Geogr. Jrnl. 59 310 In the upper Val de Conches..it is found that 57 per cent. of the unproductive area and 61 per cent. of the forested area lie within the ubac. 1937A. Garnett Insolation & Relief ((Inst. of Brit. Geographers Publ. No. 5)) i. 4 While ubac air temperatures may be 2 degrees lower in winter than the adret air temperatures, this difference diminishes in summer to zero, and may in some cases give ubac air temperatures that are even slightly warmer. 1963D. W. Humphries & E. E. Humphries tr. H. Termier & G. Termier Erosion & Sedimentation ii. 38 Given that a more rapid thawing occurs on the adret than on the ubac solifluction is most strongly developed on the less sunny slope. 2000G. Barker Archaeology of Drylands 317 South-facing adret slopes receive 50 per cent more sunshine than north-facing ubac slopes. |