Assessing topographic exposure

Topographic exposure is a variable which represents the degree of shelter a fforded to a location. A detailed knowledge of exposure is useful for a wid e variety of applications, ranging from the dynamics of drifting snow to th e optimal location of wind-farms. The degree of exposure can be calculated by considering the relative heights and distances of the horizon surroundin g the point of study. Numerous approaches have been developed to measure th is useful variable, from the early qualitative studies of wind-shaped trees to Pyatts's quantitative TOPEX assessment. However, these studies have bee n superseded by the use of computers and in particular the application of d igital terrain models. These provide a fast office-based solution, virtuall y eliminating the need for fieldwork.