听力填充: Precipitation refers to any form of water particles that form in the atmosphere and fall to the ground. It has a profound impact on (1) ______ . Depending on the form of precipitation, it can reduce visibility, create (2) ______ , and affect landing and takeoff performance of an aircraft. Precipitation occurs because water or ice particles in clouds grow in size until the atmosphere can no lon ger support them. It can occur in (3) ______ as it falls toward the Earth, including drizzle, rain, ice pellets, hail, and ice. Drizzle is classified as very small water droplets, smaller than 0.02 inches in diameter. Drizzle usually accompanies fog or (4) ______ . Water droplets of larger size are referred to as rain. Rain that falls through the atmosphere but (5)______ prior to striking the ground is known as virga. Freezing rain and freezing drizzle occur when the temperature of the surface is below freezing; the rain freezes on contact with the cooler surface. If rain falls through a temperature inversion, it may freeze as it passes through the underlying cold air and fall to the ground in the form of ice pellets. Ice pellets are an indication of a temperature inversion and that freezing rain exists at a (6) ______ . In the case of hail, freezing water droplets are carried up and down by drafts inside clouds, growing larger in size as they come (7) ______ more moisture. Once the updrafts can no longer hold the freezing water, it falls to the Earth in the form of hail. Hail can be pea-sized, or it can grow as large as 5 inches in diameter, larger than a softball. Precipitation in any form poses a threat to safety of flight. Often, precipitation is accompanied by (8) ______ and reduced visibility. Aircraft that have ice, snow, or frost on their surfaces must be carefully cleaned prior to beginning a flight because of the possible airflow disruption and (9) ______ . Rain can contribute to water in the fuel tanks. Precipitation can create (10) ______ on the runway surface itself, making takeoffs and landings difficult, if not impossible, due to snow, ice, or pooling water and very slick surfaces.