8.24 Precipitation

8.24.2 Define:

(a) precipitation;

Precipitation is any form of liquid or solid water that falls from cloud and reaches the Earth’s surface.

It includes:

• Rain
• Drizzle
• Snow
• Sleet
• Hail

Precipitation occurs when water droplets or ice particles become large and heavy enough that they can no longer remain suspended in the atmosphere.

(b) virga.

Virga is precipitation that falls from cloud but evaporates before reaching the ground.

It may be seen as streaks or shafts of precipitation below cloud, but no precipitation is observed at the surface.

8.24.4 Describe the following types of precipitation:

(a) rain;

RA

Rain consists of liquid water droplets with a diameter of 0.5 mm or greater.

Rain may fall steadily from layered cloud or occur as showers from cumuliform cloud.

(b) drizzle;

DZ

Drizzle consists of very small liquid water droplets, less than 0.5 mm in diameter.

The droplets are close together and usually fall from low-level stratus cloud. Drizzle often reduces visibility.

(c) snow;