Rain and Snow

Rain is liquid precipitation that usually forms in either nimbostratus clouds or cumulonimbus clouds. Snow is precipitation in the form of ice crystals called snowflakes. The size and shape of snowflakes depend on the temperature at which they form.

Figure 18 Freezing rain creates beautiful effects but can be dangerous.

Hail, Sleet, and Freezing Rain

Hail is precipitation in the form of round, solid pieces of ice more than 5 millimeters in diameter. Hail forms within cumulonimbus clouds when small ice pellets are tossed up and down by rising and falling air. As the ice is tossed about, it collides and combines with water droplets that then freeze, creating more and more layers of ice. Eventually, the ice becomes heavy enough to fall to the ground as hail. Hail can sometimes cause tremendous damage to crops, vehicles, and buildings.

Sleet is precipitation in the form of ice particles that are usually smaller than 5 millimeters in diameter. Sleet is rain that freezes as it falls. Sleet rarely damages crops or vehicles directly, but it can make driving extremely hazardous.

Freezing rain is rain that freezes after hitting the surface. Freezing rain produces beautiful effects, as Figure 18 shows, but it can be dangerous. Roads become very slippery, and branches or power lines can fall from the weight of the ice.