Chapter 08
FIGURE 8.1 Correlation between vertical velocity and potential temperature perturbations for upward or downward parcel displacements when the mean potential temperature θ0(z) decreases with height.
FIGURE 8.2(a) Mean potential temperature, θ0, and (b) mean zonal wind, U, profiles in a wellmixed boundary layer. (Adapted from Stull, 1988.)
FIGURE 8.3 Balance of forces in the well-mixed planetary boundary layer: P designates the pressure gradient force; Co, the Coriolis force; and FT, the turbulent drag.
FIGURE 8.4 Hodograph of wind components in the Ekman spiral solution. Arrows show velocity vectors for several levels in the Ekman layer; the spiral curve traces out the velocity variation as a function of height. Points labeled on the spiral show the values of γz, which is a nondimensional measure of height.
FIGURE 8.5 Mean wind hodograph for Jacksonville, Florida (≅30°N), April 4, 1968 (solid line) compared with the Ekman spiral (dashed line) and the modified Ekman spiral (dash-dot line) computed with De ≅ 1200 m. Heights are shown in meters. (Adapted from Brown, 1970. Copyright © American Meteorological Society. Reprinted with permission.)
FIGURE 8.6 Schematic surface wind pattern (arrows) associated with high- and low-pressure centers in the Northern Hemisphere. Isobars are shown by thin lines, and "L" and "H" designate high- and low-pressure centers, respectively. (After Stull, 1988.)
FIGURE 8.7 Streamlines of the secondary circulation forced by frictional convergence in the planetary boundary layer for a cyclonic vortex in a barotropic atmosphere. The circulation extends throughout the full depth of the vortex.
FIGURE 8.8 Streamlines of the secondary circulation forced by frictional convergence in the planetary boundary layer for a cyclonic vortex in a stably stratified baroclinic atmosphere. The circulation decays with height in the interior.