. Compendium of meteorology. Meteorology. 1276 RADIOMETEOROLOGY because winds aloft are usually fairly uniform. Deter- mination of the direction and speed of the cells is gener- ally quite simple, especially if the cells are fairly well defined so that their positions may be determined at ten or fifteen minute intervals. It has been observed in the northeastern United States that warm-sector precipitation, besides being broken into small convective cells, usually consists of rather large, isolated areas. That is, a precipitation Tea of roughly elliptical shape, perhaps 100 miles in ex+ent, wil
. Compendium of meteorology. Meteorology. 1276 RADIOMETEOROLOGY because winds aloft are usually fairly uniform. Deter- mination of the direction and speed of the cells is gener- ally quite simple, especially if the cells are fairly well defined so that their positions may be determined at ten or fifteen minute intervals. It has been observed in the northeastern United States that warm-sector precipitation, besides being broken into small convective cells, usually consists of rather large, isolated areas. That is, a precipitation Tea of roughly elliptical shape, perhaps 100 miles in ex+ent, will be broken up into small-size cells of 1-5 miles diameter. The large areas follow each other through the region covered by the radar sweep, with almost no isolated showers occurring between them or on the fringes of the main groups. 2. Thunderstorms. The appearance of a thunderstorm echo signal on PPI and RHI scopes is similar to that shown in Fig. 6. These storms, because of their great height, are detectable at greater distances than any other type of precipitation. Well-developed storms have been detected at distances over 300 miles, although for a radar less than 100 ft above the surrounding coun- try, the usual maximum range is nearer 200 miles. Radar played an important role in the extensive re- search program on thunderstorms in Florida and Ohio [60-62]. Using radar it is possible to determine when a given convective cell reaches the thunderstorm stage. Light- ning gives a characteristic echo signal on A and R scopes as shown in Fig. 14 [39]. The echo signal from The best presentation of thunderstorm echo signals is found on the RHI scope, as shown in Fig. 15. Again, the reader is cautioned to keep in mind the 10:1 vertical. Fig. 14.—Photograph of R scope showing lightning echo signal. Low intensity echo signal from precipitation to- right and left of lightning echo signal which persisted for about Ji sec. (1510 EST, 7/20/49, S-band radar, azimuth 320°, range 50-58 m
Size: 1829px × 1367px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectmeteorology
