Foehn wind environment with strong and gusty winds. Explanations of the foehn warming and drying effect in popular literature or on the web often single out just one causal mechanism (#1 - Condensation and Precipitation - in the below), but there are in fact four known causes (illustrated in the schematic at top right of this page). These mechanisms often act together, with their contributions varying depending on the size and shape of the mountain barrier and on the meteorological conditions, for example the upstream wind speed, temperature and humidity. 1) Condensation and precipitation: When air is forced upwards over elevated terrain,
Dirichlet boundary condition Dirichlet boundary condition In mathematics, the Dirichlet (or first-type) boundary condition is a type of boundary condition, named after Peter Gustav Lejeune Dirichlet (1805–1859). When imposed on an ordinary or a partial differential equation, it specifies the values that a solution needs to take on along the boundary of the domain. The question of finding solutions to such equations is known as the Dirichlet problem. In applied sciences, a Dirichlet boundary condition may also be referred to as a fixed boundary condition. For an ordinary differential equation, for instance, the Dirichlet boundary conditions on the interval take the form where