Orographic precipitation

Orographic precipitation processes strongly shape the climate in and around mountainous regions. Orographic influences can be pronounced on spatial scales ranging from the size of individual hills to the scale of major mountain ranges, and on temporal scales from the duration of a brief snow squall to the long-term climatology. Almost all orographic influences are fundamentally caused by topographically driven ascending and descending atmospheric motions that force condensation and evaporation. However, these basic forcings combine with a wide range of dynamical and microphysical processes to shape the precipitation distribution. Since different physical processes can be important for different storms and for different mountain ranges, orographic precipitation influences may take many forms. Characterizing and understanding the effects of topography on precipitation remains an active field of research. Current research questions include: How does orographic precipitation change with climate? How do turbulent atmospheric motions affect orographic enhancement? What are the limits on predictability of orographic precipitation? Synthesis of new theories, models, and observational techniques continues to aid us in trying to answer these and other important questions.