Rainfall

3925

Rain-in-the-Face

from the atmosphere in either the liquid or
solid condition, The quantity of water that
can exist in the atmosphere as a vapor varies
with the temperature. When the maximum
amount of vapor for any given temperature
is present, the vapor is said to be saturated;
and if the air is cooled below the point of
saturation, a part of the vapor is condensed,
and will fall as rain. Precipitation is facili-
tated by the presence of nuclei on which the
drops of water form. These nuclei of con-
densation may be minute solid cr liquid par-
ticles, or even the ions resulting from th*1
dissociation of atmospheric molecules. When
condensation takes place below the freezing
point, snow is formed. Snow, if melted, will
yield in water, on the average, one-tenth of
its original depth.

The cooling of-air necessary for condensa-
tion may take place in the following ways:
(r) by contact of the air with colder land or
water surfaces; (2) by the radiation of heat
into space or to the earth; (3) by the mix-
ture of comparatively warm and moist air
with that which is colder and drier; (4) by
the cooling of air due to its own expansion
when it passes into a region of lower atmo-
spheric pressure, cither as an ascending cur-
rent due to the displacement of heated lower
air by colder air from above, as a part of the
revolving and ascending winds in an area of
low barometric pressure, or by the more di-
rect ascent when forced up a mountain slope.
The last named process is very effective in
the formation of clouds and rain, and the re-
gions of heaviest rainfall arc found where
moisture-laden winds from the ocean are de-
flected upward by mountain ranges. It fol-
lows that the distribution of rainfall is largely
influenced by the direction of the prevailing
winds, the occurrence of cyclonic storms, the
topography of the land surface, and the re-
lation of land and water areas.

In summer the continents arc hotter than
the oceans, and the surface winds tend to
blow from the sea to the land; in winter both
of these conditions are reversed. The move-
ment of the sun north and south of the equa-
tor causes a corresponding north and south
periodic shift of the wind belts and tempera-
ture zones. All these causes combine to pro-
duce seasonal variations in rainfall, resulting
in some localities in wet and dry seasons.

There is a normal increase of rainfall with
altitude up to a certain point, above which
it again decreases, on account of the smaller
capacity for water vapor of the colder upper
strata. The heaviest annual precipitation in

the United States is found in western Wash-
ington and north-western Oregon, with an
average of 80 to 100 inches. It sometimes ex-
ceeds 126 inches for a single year at Neah
Bay, Washington, and in 1896, at Glenora,
Oregon, situated at a moderate elevation in
the Coast Range, it%amounted to 169 inches.
The coast rainfall decreases rapidly toward
the s., falling to 22 inches at San Francisco
and to rather less than this amount at San
Diego.

The great masses of the Sierra Nevada and
Cascade Mts. extending at right angles to the
prevailing winds, deprive the states to the
eastward of the rain that falls abundantly on
their western slopes, and the plateau lying
between these ranges and the Rockies is the
most extensive arid region of the United
States. On the eastern slope of the Rocky
Mts. the rainfall is at first deficient, but in-
creases steadily as we go eastward, amounting
Lo from 48 to 60 inches over the greater part
of the Gulf and S. Atlantic states, with a
maximum of 70 in limited areas of Georgia
and the Carolinas, where moisture from the
Gulf of Mexico and the Atlantic is deposited
on the slopes of the Appalachians.

Rain-gauge, an instrument for measuring
rainfall, consisting of a cylindrical, vertical
metal vessel, whose sharp-edged top, of
known diameter, is connected with a funnel
that conducts the rain into an inner vessel.

Rainer, Luise (1911- ), Austrian ac-
tress. She won favor in Saint Joan, American
Tragedy and Men in White. In 1935 she
made her debut on the screen in Escapade.
Her appearances as Anna Held in The Great
Ziegfdd (1936) and 0-lan in The Good
Earth (1937) enhanced her reputation. She
married Clifford Odets in 1936. In 1936 and
1937 she won the Award of the New York
Dramatic Critics.

Rainier, or Tacoma, Mount, a mountain
on the w. flank of the Cascade Range, in the
s. part of Pierce co., Wash., about 41 m. s.e.
of Tacoma city. It is a dormant volcano. The
imposing cone towers 14,363 ft. above sea
level. Thick forests cover the lower region of
the mountain, while higher up there are 14
glaciers. Vancouver discovered Rainier in
1792 and named it in honor of Rear-Admiral
Rainier, of the British Navy.

Rain-in-the-Face (?-i90$), a chief of the
Uncpapa tribe of the Sioux Indians, who
came into prominence in 1876 as a leader in
the Sioux outbreak of that year in the Yel-
lowstone region, when the Indians surround*
ed and killed Gen. George A. Custer and fiv*