The development of atmospheric cyclones is studied from the viewpoint of the instability of large-scale wave perturbations superimposed on a zonal current.

A time-dependent, hemispheric, primitive-equation numerical model is constructed to test Hines' (1974) hypothesis that solar variations induce changes in the distributions of basic state variables at high levels in the atmosphere, and thus induce changes in planetary-scale wave structure at lower atmospheric levels. This mechanism was proposed to explain apparent atmospheric responses to solar activity.

The present study is designed to provide both a method whereby the details of the nonlinear exchange process which occurs in the atmosphere may be considered in a simplified form, and also to indicate from some calculations the complexity of those exchanges.

A case study of the 26-27 June 1985 PRE-STORM Mesoscale Convective System (MCS) is presented. The system was analyzed using the dense surface and upper-air observations available from the PRE-STORM field program.

The influence of vertical wind shear on the development and structure of hailstorms occuring in Northeastern Colorado was examined in this study.

A generalization of the two-dimensional spectral forecast equations is suggested, whereby the atmospheric flow field in horizontal and vertical directions is represented in terms of orthogonal functions, which are eigenfunctions of certain differential operators in the three-dimensional equations. The technique is applied to the quasi-geostrophic potential vorticity equation.

In order to simulate the climate of an ice age, a two-level, quasi-geostrophic, spectral general circulation model for the northern hemisphere is developed.

A preliminary climatology of mesoscale convective complexes (MCCs), based on satellite data from two warm seasons, indicates that these systems frequently affect United States agricultural regions and it is hypothesized that MCCs produce a highly significant portion of the growing season precipitation over these areas.