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,
Weather front If the air mass is colder than the ground below it, it is labeled k. If the air mass is warmer than the ground below it, it is labeled w. Fronts separate air masses of different types or origins, and are located along troughs of lower pressure. A surface weather analysis is a special type of weather map which provides a view of weather elements over a geographical area at a specified time based on information from ground-based weather stations. Weather maps are created by plotting or tracing the values of relevant quantities such as sea-level pressure, temperature, and cloud