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In physical geology, aspect is the compass direction that a slope faces.〔National Wildfire Coordinating Group, Basic Land Navigation, ()〕 For example, a slope on the eastern edge of the Rockies toward the Great Plains is described as having an ''easterly aspect''. A slope which falls down to a deep valley on its western side and a shallower one on its eastern side has a ''westerly aspect'' or is a ''west-facing slope''. The direction a slope faces can affect the physical and biotic features of the slope, known as a slope effect. The term aspect can also be used to describe the shape or alignment of a coastline. Here, the aspect is the direction which the coastline is facing towards the sea. For example, a coastline with sea to the northeast (as in most of Queensland) has a ''northeasterly aspect''. ==Importance of aspect== Aspect can have a strong influence on temperature. This is because of the angle of the sun in the northern and southern hemispheres which is less than 90 degrees or directly overhead. In the northern hemisphere, the north side of slopes is often shaded, while the southern side receives more solar radiation for a given surface area insolation because the slope is tilted toward the sun and isn't shaded directly by the earth itself. The further north or south you are and closer to winter solstice the more pronounced the effects of aspect of this are, and on steeper slopes the effect is greater, with no energy received on slopes with an angle greater than 22.5° at 40° north on December 22 (winter solstice).〔Barbour, et al. (1999) ''Terrestrial Plant Ecology, 3rd Ed.'' Benjamin/Cummings. Chapter 14. pp. 390-391〕 The aspect of a slope can make very significant influences on its local climate (microclimate). For example, because the sun's rays are in the west at the hottest time of day in the afternoon, in most cases a west-facing slope will be warmer than a sheltered east-facing slope (unless large-scale rainfall influences dictate otherwise). This can have major effects on altitudinal and polar limits of tree growth and also on the distribution of vegetation that requires large quantities of moisture. In Australia, for example, remnants of rainforest are almost always found on ''east-facing slopes'' which are protected from dry westerly wind. Similarly, in the northern hemisphere a south-facing slope (more open to sunlight and warm winds) will therefore generally be warmer and dryer due to higher levels of evapotranspiration than a north-facing slope. This can be seen in the Swiss Alps, where farming is much more extensive on south-facing than on north-facing slopes. In the Himalayas, this effect can be seen to an extreme degree, with south-facing slopes being warm, wet and forested, and north-facing slopes cold, dry but much more heavily glaciated. For a farmer, thus, choosing an aspect that will shelter from hot, dry winds or from cold can be critical to successful growth of crops. Most farming agencies will state in manuals whether a crop prefers a pole ward or equator ward aspect (if this is important). Glaciology is also influenced by aspect: unless precipitation patterns dictate otherwise (as in Iceland where glaciers accumulate on the much wetter south-western side) glaciers always accumulate downwards on the pole ward side of mountains. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Aspect (geography)」の詳細全文を読む スポンサード リンク
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