Weather, Climate, and Topography
This paper presents a review of recent progress on the theory of orographic precipitation and a discussion of the role of preexisting atmospheric disturbances, especially their strong water vapor fluxes. I also introduce the basic elements of stable moist airflow dynamics and cloud physics, and a new linear theory of orographic precipitation. The theory is tested against two types of data: a single event of Alpine precipitation and the annual climatology of the Oregon coastal ranges. Different methods are used to determine the free “cloud-delay” parameters in the theory, including a statistical analysis of data from conventional rain gauges and isotope analysis of stream samples. The surprising threshold behavior of nonlinear accretion-dominated cloud physics is displayed. Finally, I consider the impact of scale-dependent precipitation patterns on erosion and terrain evolution.