1. An aircraft-based weather information sharing and display system comprising: at a ground station: reception equipment for receiving weather parameters from a plurality of weather-sensing sources; processing equipment for generating a refined weather information report, based on said received weather parameters, using data compression techniques to reduce the size of said weather information report; and transmission equipment for uplinking said refined data-compressed weather information report to a plurality of aircraft and at an aircraft: standard weather information gathering equipment for detecting local weather parameters characterizing a weather condition in the vicinity of the aircraft; transmission equipment for transmitting said local weather parameters to said ground station; reception equipment for receiving said refined data-compressed weather information report uplinked by said ground station; storage equipment for storing received said weather information report and said detected local weather parameters; picture generating equipment for generating symbolic pictorial information based on the received refined weather information and said detected local weather parameters; and weather information display equipment, coupled to the picture generating equipment, for displaying pictorial polygons indicating the dynamic behavior of said weather condition.