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).


  • Discussion


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).



  • Units


    Aspect is commonly measured as a compass bearing in degrees clockwise from true North. Four, eight, or 16 cardinal directions may also be used to identify aspect. The relationship between these cardinal directions and degrees clockwise from uphill are shown on this conversion table.


  • See Also

  • References

    • American Meteorological Society (AMS). 2000. Glossary of Meteorology. [Online]. Available:

    • Andrews, P.L. 1996. Fire behavior. In: Pyne, S.J.; Andrews, P.L.; Laven, R.D. Introduction to Wildland Fire. 2d ed. New York, NY: John Wiley and Sons: Chapter 2.

    • Whiteman, David C. 2000. Mountain Meteorology: Fundamentals and Applications. New York, NY: Oxford University Press, Inc. 355 pp.


  • Notes

    • Author 

      Charles W. McHugh, Fire Spatial Analyst

      Rocky Mountain Research Station