This report consists of three separate papers concerned with the climatology of jet streams and clear-air turbulence. The first paper is entitled 'Jet-Stream Structure over the Central United States Determined from Aircraft Observations.' In this study, empirical models of jet streams are found to agree well with previous models based on data from other regions of the mid-latitudes. Also, we found that variations in the speed field with season and with position in the upper flow pattern were rather small, so that a single model describes the jet stream adequately. The second paper is entitled 'Empirical Relationships Between Gust Intensity in Clear-Air Turbulence and Certain Meteorological Quantities.' This paper provides data of a type that has not been available previously, having applications to aircraft and missile design, and to the determination of world-wide turbulence statistics. The third paper is entitled 'Some Autocorrelations and Spectra of Wind and Temperature in Jet Streams.' Correlations were computed for paths oriented across jet streams and along jet streams. In all cases, the autocorrelations decreased to zero within 25 to 40 percent of the path length, indicating that the distance considered (length of the data sample) is important in determining the shape of the autocorrelation function. Spectral computations showed that only a small portion of the variance lies in the mesoscale range--i.e., in wavelengths smaller than approximately 200 nm. (Author).