Snow cells and showers.

One of the notable contributions of radar to the study of precipitation has been the revelation of the fact that much of the precipitation which reaches the ground as continuous rain or snow has its origin aloft in compact and discrete cells, whose horizontal dimensions may be of the order of a mile or so and which extend vertically for several thousands of feet. Marshall (1953) published RHI* photographs of such cells and the snow trails which derive there from, and formulated the geometry of the trail shaped in the wind field; similar analyses were performed independently by L’hermitte (1952) and Browne (1952)