Abstract: Numerous environmental processes affect the development and stability of playa (lakebed) surfaces. Of special significance are hydrologic processes that control the amount and flow of both surface and ground water, and climatic variations which in turn influence the hydrology. This report, in six parts, examines some aspects of the playa surface environment. Chapter 1 is an introduction. Chapter 2 describes microrelief changes that developed at Harper Playa, California, following flooding of the playa in 1965-66. Chapter 3 documents a subsurface hydrologic investigation at Rogers Playa, California. The investigation revealed that the piezometric surface has lowered into sand layers beneath the surface, and it may explain why giant desiccation fissures have formed in the surface clays. Chapter 4 describes an investigation of seven Australian playas and suggests that Australia did not undergo a pluvial period like that of the western United States. Chapter 5 describes three kavirs (playas) in northern Iran and indicates that former lakes did exist there, but not to the same extent as in the western United States. Chapter 6 examines the possibilities of observing playa surface changes from satellites, using the present remote sensor technology. It also states that Gemini color photography and high resolution vidicon …

Abstract: This Survey is divided into four parts: (a) a representation of winds of space and time, which includes a tool for analysis, called the "geostrophic-gradient divider", and the "2-prog" and "4-prog" charts ; (b) flight planning tools: the 4-D plotter and the fixed-speed time-front plotter ; (c) methods of flight planning, including fixed-track flight planning, single-drift flight planning and emphasizing minimal flight planning, and (d) an interpolative system of minimal flight planning. Included are three appendices to do the following: (a) to derive the basic equation of minimal flight planning, to show why time fronts should be drawn omitting the crosswinds, and to show why time fronts prepared from one airspeed can be used on minimal flight paths with another airspeed ; (b) to show the advantage of 4-prog charts or derived 2-prog charts in representing vertical wind shears that are changing with time, and (c) to report on tests of the recommended procedures.