rain, precipitation in liquid form. It consists of drops of
water falling from clouds; if the drops are very small, they
hydrologic, or water, cycle in which moisture from the
oceans evaporates, condenses into clouds, precipitates
runoff into streams and rivers to begin the cycle again.
snow, precipitation formed by the sublimation of water
vapor into solid crystals at temperatures below freezing.
Sublimation resulting in the formation of snow takes place
about a dust particle, as in the formation of raindrops.
Snowflakes form symmetrical (hexagonal) crystals,
sometimes matted together if they descend through air
warmer than that of the cloud in which they originated.
named according to the point of the compass from which it
blows, e.g., a wind blowing from the north is a north wind.
rotating air that develops below a heavy cumulonimbus cloud
mass and extends toward the earth. The funnel twists about,
destruction. The diameter of a tornado varies from a few feet
to a mile; the rotating winds may attain velocities of 200 to 300
mi (320–480 km) per hr, and the updraft at the center may
reach 200 mi per hr.
accompanied by lightning, thunder, and heavy rain, often
typical thunderstorm caused by convection occurs when
the sun's warmth has heated a large body of moist air near