RAIN for waterbug the nerd all dried up in Az,lol!
Rain is liquid
precipitation, as opposed to non-liquid kinds of precipitation such as
snow,
hail and
sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface. On Earth, it is the
condensation of atmospheric
water vapor into
drops of
water heavy enough to fall, often making it to the surface. Two processes, possibly acting together, can lead to air becoming saturated leading to rainfall: cooling the air or adding water vapor to the air.
Virga is precipitation that begins falling to the earth but evaporates before reaching the surface; it is one of the ways air can become saturated. Precipitation forms via collision with other rain drops or ice crystals within a
cloud. Large rain drops are
oblate-shaped and small drops are spherical. Moisture moving along three-dimensional zones of temperature and moisture contrasts known as
weather fronts is the major method of rain production. If enough moisture and upward motion is present, precipitation falls from convective clouds (those with strong upward vertical motion) such as
cumulonimbus (thunderstorms) which can organize into narrow
rainbands. In mountainous areas, heavy precipitation is possible where
upslope flow is maximized within
windward sides of the
terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains. On the leeward side of mountains, desert climates can exist due to the dry air caused by downslope flow which causes heating and drying of the
air mass. The movement of the
monsoon trough, or
intertropical convergence zone, brings
rainy seasons to
savannah climes. Rain is the primary source of freshwater for most areas of the world, providing suitable conditions for diverse
ecosystems, as well as water for
hydroelectric power plants and crop
irrigation. Rainfall is measured via
rain gauges. Rainfall amounts can be estimated by
weather radar.