Deseret evening news. [volume] (Great Salt Lake City [Utah]) 1867-1920, 1908-07-04

area OF low pressure docs not cNtcnu
TO very great height above the earth,
but its horizontal extent may be humid
reds of miles. 90 Southeast of this
storm center the winds blow from the
southwest and south, northwest from
the center. they come from the east
and northeast: north OF the center they
come almost from the north; and on
the west side OF the center, from the
northwest. t6) The central area of low
pressure advances eastward at the
rate of 600 miles per duy but inclines
TO the southeast. For us IL begins in
the vicinity of oregon and Washing
ton. The storm center usually falls to
invade the Great Basin. II passes south
east, sometimes to the Gulf and some
time only to Montana. III the latter
case. IL traverses the Great lakes on
Its way TO the Atlantic.
CYCLoNIc WEATHER IN THE PLA-
TiSAU.
Though the Rocky mountains inter-
copt the prevailing winds nearly at
right angles, yet since the prevailing
westerly winds are relatively warm
during most of the year, and the as
cent from the Great Basin to the sum-
mlts of the continental divide is grad
ual. the cooling effect due to elevation
Is not so noticeable in the plateau re-
gions as 1t would otherwise be. The
flow of warm currents from the Pacific
Is 'but little retarded, and temperatures
are often higher IN winter on the sum-
nts than on the lowlands farther east
Cold waves of winter (anti-cyclones)
originate in the region north OF Nom
tana and travel southeast. The cyclone,
or storm, is warmest at the southwest
quadrant or front of the storm, and
coolest on the northwest quarter circle
or rear; or II is warmest ON the east
and coolest on the west side, when the
trough of low pressure extends due
north and south. In winter these tenn
peratures average IS degrees on the
northwest; on the southwest, "a; south
east, 40; and northeast, 20. The rain
areas attending the cyclone are very
irregular. With us, southeast WINDS
precede the storm. These warm the
air, and make 1t light and moist, before
the cold air from the Pacific northwest
approaches. They sky becomes over
cast. and rain or snow falls; then the
winds come from the west and cold
wave follows. Heavy air and clear
skies, with wind circulation directly
opposite to that in the cyclone and
hence called the anti-cyclone, now pre-
vail. Cyclone and anti-cyclone together
last about three days. Cyclonic weather
means cloudy skies and warm air. fot'
lowed by rain or SNOW; anti-cyclonic
and fair skies. The southern half OF
the plateau-Colorado Utah. Arizona,
New Mexico and southern California
are less frequently visited by cyclonic
disturbances than the northern half
and the winds from the Pacific bring
little moisture The fall in temperature
In the rear of the cyclone is not so pro-
nounced on the Pacific coast and over
the plateau as 1t Is In districts east of
the Rocky mountains. The air in front
OF a cyclone is heated by the warm
winds from the south and by local
cloudiness which prevents the heat
from radiating from the ground.
In winter an anti-cyclone. or period of
cold. clear weather will often remain
stationary for days over the plateau
without passing east OF the Rockies.
This condition Is often accompanied by
easterly winds. Its cause has not yet
been explained.
CLIMATIC CHANGES OF THE
PLATEAU.
The fossil beds of wyoming, and, In
n small degree, of Utah, tend TO snow
that the great climatic changes 10
which the earth has been subject IN
ages mast have been very marked IN
the plateau region. Skeletons OF
enormous animals that lived mere
when the climate was much cooler and
much more moist and of others that
were here when the climate was much
warmer than II now Is, are the most
striking evidences to the non-scien-
tific reader of the climatic changes.
But other indications, more general IL
less striking, are not difficult to md
Ii is known that repeated changes In
climate have occurred in the Rocky
Mountain areas, and that the records
left by the former lakes of the Great
Basin constitute the greatest body OF
evidence in establishing this fact.
Gilbert has shown that there were
five stages in the history OF Lake
Bonneville. The first was n long per-
iod of drier climate and Of low water.
during which alluvial cones. now more
or less buried by later lake deposits,
were built along the bases of the
mountain ranges enclosing the lake.
The second was period OF moister
climate and of high water, which,
however. did not result in overflow
The third period was one OF complete
drying IN of <he lakes. after which
the deposits of the rivers were not
made in water but on the land of the
dry valleys. There was a fourth peri
cd in which the water rose again TIL
it overlooked at the northeast corner
of the Basin. The lake water then
was perhaps 9S5 feet above the pres
ent level of the lake, and channel