vertical visibility

例句：

1. 1. The pilot was able to maintain a high vertical visibility during the flight.
   飞行员在飞行中能够保持很高的垂直能见度。
2. 2. The mountain range is so vast that it can be difficult to determine the true vertical visibility.
   这个山脉如此辽阔，很难确定真正的垂直能见度。
3. 3. In order to ensure safe operations, the aircraft must maintain a minimum vertical visibility of 500 feet.
   为了确保安全操作，飞机必须保持至少500英尺的垂直能见度。