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The paper presents results of a series of studies of Upper Midwest hailstroms made between 1957 and 1962. It discusses hailstorm frequency, incidence, origins and formation in the Upper Great Plains of the United States, but omits synoptic considerations since they were discussed in an earlier paper.

Data for fifty high-altitude balloon flights made by Raven Industries, Inc. between January, 1957, and October, 1960, have been released for analysis. Raven flight altitudes and trajectories supplement those used by A. D. Belmont. They serve to confirm and in a few instances to modify his “meanwhile” conclusions, based on the data currently available.

Hail damage at the ground, plotted from insurance records for ten years of crop season hall storms, is found to fall into recognizable pattern groups, associated with specific features of the synoptic map. Speed of movement of the synoptic systems appears to exert considerable influence on the extent and degree of ground hail damage.

This paper is a review and compilation of information concerning the incidence and frequency of hail fall in tropical areas. The authors have gathered the data over a period of years from literary sources and by extensive correspondence with private individuals and government meteorological services. The four areas under which the various hail reports are grouped, viz., the American, African, Asian, and Australian, together form a total band around the Earth within latitudes 23½ degrees north and south of the equator. Attempts have been made to systematize presentation of the information. This is possible only up to a point, however, since it was received in a multiplicity of forms, some of which defy conventional climatological handling. Nevertheless, the paper makes possible for the first time a comprehensive assessment of the tropical hail phenomenon. Moreover, a great deal can be learned from it about seasonality of hail fall in specific areas and about the occurrence of hail at sea level and...

Two studies have been made utilizing the data included in the four appendices to the original report with the same title. The first study relates hailstorm frequency and station altitude; the second discusses hail regimes within the tropics.

DURING the night of October 31/November 1, 1967, a sudden change in the structure of amplitude scintillations of radio signals from the S-66 BEC satellite was observed at Fort Monmouth. Observations made at 41, 40 and 20 MHz are indicated in Fig. 1, which relates to orbit 12239; the satellite was passing in a west–east direction near 40° N latitude. The unusual event was manifested by (1) a train of strong and frequent amplitude scintillations which was interrupted for a short period and resumed 60 s later and by (2) a similar interruption showing also a scintillation-free zone during 44 s of the following orbit, 12240. The polarization of the signals displayed corresponding variations. Usually such short and sudden interruptions of strong amplitude scintillations are not observed with satellite signals. The geographic location of the subionospheric tracks from 350 km altitude of these two passages is shown by the dashed lines in Fig. 2. The start and end of the scintillation-free intervals, as obtained from amplitude recordings, are given in Table 1. The related total integrated electron content was obtained from measurements of a polarization follower having sampling times of 80 µs and automatic digitized printout for each time second. The electron content curves show a familiar oscillatory pattern1 which characterizes the observation of severe amplitude scintillations. During the “no-scintillations” periods shown in Table 1, the electron content followed a smooth curve.