Cloud Patterns in Hurricane Daisy, 1958

Maps of clouds in Hurricane Daisy, 1958, have been constructed from aerial ciné photographs made by the aircraft of the National Hurricane Research Project of the U.S. Weather Bureau. Films suitable for quantitative analysis were available for four flights on three separate days during the formation, deepening, and maturity of this small but intense Atlantic hurricane which moved slowly over the ocean in the vicinity of 30° N, 76° W. Clouds were located within 5–10 nautical miles relative to the known aircraft path (in coordinates with origin at hurricane center) by a modified method of aerial photogrammetry using the accurately known timer for the image to cross a frame. Horizontal and vertical dimensions of important clouds and cloud forms have been measured to within about 10 %.

The photographic maps are compared to radar analyses made from the same and also different aircraft (U.S. Navy WV-4). The most significant results are first the remarkable persistence of recognizable cloud patterns throughout the three days studied, during which the storm deepened and moved about 200 nautical miles and second, the concentration of convective activity into a few lines of cumulonimbus towers which even on the mature day occupied only about 4 % of the rain area (radius within about 200 nautical miles).