A simple analytical expression is developed to relate the energy required to initiate moist convection to boundary-layer properties. This expression and exploratory regression are applied to data from the National Hail Research Experiment to discriminate between environments leading to cumulus congestus and well-developed hail-producing thunderstorms in northeast Colorado.
In this...
An analytical two-layer approximation of atmospheric flow is developed to study boundary-layer production of vertical motion. The model consists of a boundary layer topped by a free-flow layer. Both layers am time-dependent and possess different values of stratification. The boundary-layer equations are layer-integrated over a fixed depth and surface stress...
Boundary-layer data from several different geographical locations are analyzed to document the behavior of boundary-layer shear above the surface. The influence of diurnal variation of stability is emphasized. The applicability of the power law for use in shear estimates is examined.
The depth of the nocturnal boundary layer, modeled by diagnostic functions of surface fluxes, is only weakly related to “observed” depths estimated from observed profiles of either wind or temperature as has been shown in previous studies. This is partly due to influences of nonstationarity and large errors in the...
Aircraft data collected at the top of a cloud-topped mixed layer during the Air Mass Transformation Experiment are analyzed. Entrainment instability due to evaporation of liquid water is found to occur intermittently. This instability and upward heat flux occur frequently at the downstream edge of cloudy mixed-layer motions which have...
Nocturnal boundary-layer data from the Wangara and Voves experiments are analyzed. The lower part of the nocturnal inversion layer normally appears to be turbulent but strongly stratified. The upper thicker part of the inversion layer is characterized by weaker stratification which appears to be almost completely generated by clear-air radiative...
The two main approaches presently in use for studying the boundary layer are quite dichotomous. It is shown that the Ekman approach which uses an eddy coefficient fixed in height can load to a serious contradiction this approach should be avoided if boundary-layer structure is being investigated.
A unified scale analysis of the momentum balance of downslope gravity flows is developed to organize previous theories for the case of negligible ambient flow and fixed temperature deficit scale. The values of several nondimensional parameters are evaluated from observations in the literature and used to assess the validity of...
The vertical distribution of density or temperature is studied in turbulent boundary layers stratified by either salt or temperature and driven in an annulus by a rotating screen. With rapidly growing boundary layers the buoyancy flux due to entrainment becomes sufficiently large that the boundary layer is no longer well...
The Penman relationship for potential evaporation is modified to simply include the influence of atmospheric stability on turbulent transport of water vapor. Explicit expressions for the stability-dependent, surface exchange coefficient developed by Louis are used. The diurnal variation of potential evaporation is computed for the stability-dependent and original Penman relationships...