Clear air turbulence data were collected from two of the four world-wide reporting periods set up by the International Civil Aviation Organization (ICAO). The occurrences and non-occurrences of turbulence were summarized with respect to time periods, altitudes, and geographical locations. These data were analyzed in relation to associated meteorological parameters and large-scale synoptic patterns. Special attention was given to areas with at least 25 percent probability of moderate or greater turbulence. Vertical wind shear appeared to be an important parameter along with 12-hour changes in wind speed, vertical wind shear, and horizontal wind shear. The synoptic patterns on the mean 300-mb charts and the individual 300-mb charts were discussed in relation to the probabilities of moderate or greater turbulence. The following forecast criteria were suggested: moderate or greater turbulence will be found (1) within 150 miles of a jet stream with at least a 100-knot maximum wind speed if the vertical wind shear is at least 4 knots per 1000 feet, or (2) within 150 miles of a sharp trough line with a marked horizontal wind shear across the trough line. (Author).

Clear air turbulence encounters can occur unexpectedly without any visual evidence or warning. As operations of higher altitude aircraft increase, the phenomenon is encountered more often. Clear air turbulence is defined as 'all turbulence in the free atmosphere of interest in aerospace operations that is not in or adjacent to visible convective activity (this includes turbulence found in cirrus clouds not in or adjacent to visible convective activity).' This bibliography consists of 578 references to technical reports, articles in periodicals, and books published during the past 17 years. References about other forms of turbulence such as that occurring with storms and airplane wake vortices are not included. (Author).

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

A practical manual for training and reference use of USAF weather forecasters who will work in the tropics, it covers basic facts of climatology, circulation, synoptic models, analysis and forecasting, application throughout the tropics. A broad survey is made of the literature, evaluated in light of the experience of the author. Physical factors controlling tropical circulations are briefly discussed. The data sources for synoptic purposes are reviewed. Climatology of pressure, winds, temperature, humidity, clouds, rainfall and disturbances is presented in a form specially suitable for forecasters. Analysis and for forecasting of disturbances, cyclones, severe weather, terminal weather, etc., are treated at length. Emphasis is placed on uses of climatology and satellite cloud photos. Over 230 figures adapted from the literature or prepared by the author serve to illustrate all the essential facts and principles discussed. A summary of the state of art and future outlook of tropical meteorology is included.