n. The cardinal direction (east, south, west, north,) or compass-bearing direction (90, 180, 270, 360 degrees) that a land slope faces (AMS 2000; Whiteman 2000).
Aspect can be easily generated within a geographic information system (GIS) using information from a digital elevation model (DEM). A spatial data layer representing aspect is required for fire modeling systems such as FARSITE or FlamMap.
Aspect affects fire behavior by influencing the amount of solar radiation, wind, and time of day that fire behavior may increase on a particular aspect (Andrews 1996). In the northern hemisphere, south and southwest aspects are most favorable for fire spread, whereas in the southern hemisphere, north and northeast aspects favor fire spread. These aspects receive more sunshine and thus have lower humidity and higher fuel temperatures (Andrews 1996).