Weather and Traffic Efficiency Weather is one of the major factors that may influence traffic capacity (交通容量). Rain, ice and snow on the runway cause potential problems for landing aircraft, and they may reduce the safe arrival rate (到达率) and require more space between landing aircraft. Fog also results in a decrease in the landing rate. These adverse weather conditions (不利气象条件), in turn, increase airborne delay for holding aircraft. If more aircraft are scheduled than which can be safely and efficiently handled in the air, a ground delay (地面延误) may be caused. This type of delay is referred to as delaying aircraft on the ground before departure due to conditions at the arrival airport. In Area Control Centers, a major weather problem is thunderstorms, which presents a variety of hazards to aircraft. To avoid thunderstorms en route, aircraft will deviate from planned routes. Such deviation would reduce the capacity of the en route system by requiring more space per aircraft, or causing congestion (拥挤) since many aircraft try to move through a single hole in a line of thunderstorms. Occasionally weather considerations cause delays to aircraft prior to their departure as routes are closed by thunderstorms. The controllers should keep a close watch on the weather and report to the meteorological observer (气象观察员) without delaying any sudden or unexpected deterioration observed, or obtained from pilots. The controllers may also obtain weather observations from aircraft. At the same time, there are new software and equipment brought in to relieve the traffic flow (交通流量) problems caused by adverse weather conditions. For instance, many ACCs are upgrading their flight strips (飞行进程单) or replacing flight strips with electronic data presented on the computer screen. These new equipment could efficiently reduce the controllers' workload by reducing the potential risks brought about by unexpected weather conditions. (289 words)