Influence of external winds and cloudiness on the transition layer above nocturnal valley drainage

Past observations in mountain valleys during nighttime drainage conditions show the existence of a dynamically active transition layer between the locally-driven drainage flow and the upper free stream airflow. The height variations in this transition layer are analyzed with respect to external wind conditions, cloudiness, and weather. Data sets from the 1982 and 1984 Department of Energy's Atmospheric Studies in Complex Terrain (ASCOT) field experiments in Brush Creek Valley, Colorado, are used in this analysis of the transition layer.