The Wilmington morning star. [volume] (Wilmington, N.C.) 1909-1990, 1946-03-11

YOU. that the breakup OF "iatei
brings warm cloudy days; 50 a
| cloudy Feb. 2 suggests that winter
might be breaking up.
! And then he is apt to REMIND
~ that one days weather Is not
fair test. H.
To understand the work OF the
.as+herman. one has to first OF
III, recognize the one chief dii-
ference between weather ana ell
mate The character of climate is
fixed chiefly by heat from the sun.
and If changes gradually with the
seasons. But weather changes
quickly as Bodies Of air with diff
ferent amounts Of heat and moist
IRE are carried here and there
over the earth by the winds. Tenn
nerature, moisture, and winds are
therefore the chief weather ele-
Iments.
And that undoubtedly is the rea-
son for all the gadgets, ,gimmicks
and graphs which adorn the tables
and walls of the Weather Bureau.
The course Of rain, wind, heat and
cold are plotted on maps, dotted
here and there with isotherms and
isobars, based on the reports re-
ceived of weather conditions all
over the world at 8 a. M, and .
To- M, eastern standard time. The
isotherms are lines connecting all
places reporting the same tempera-
ture (the name. comes from the
Greek word isos, equal" and
therme, 'heat.") A line joining
places having the same barometric
pressure is an INSOFAR (from the
Greek isos equal" and baros,
weight. The insobars show the
highs and lows; arrows show wind
directions.
The remaining great factor II
seather is moisture, or lack OF it,
the Weatherman may, or likely
will, point out if one should ask
him. Warm air sucks up moisture
and holds it as water vapor. When
the air cools, it cannot hold all the
vapor, and the excess is squeezed
out, or precipitated, as rain, snow,
frost, or dew. A cyclone travelling
across the country acts like great
pump, drawing in moisture-laden
winds from the east, southeast, and
south, and cooling the air as II
rises until moisture is precipitateo
from the center of the storm.
Snow Melted
On the weather map, amounts Of
precipitation are shown in hum
dredths Of inches Of rain: snow is
sometimes melted to water for
this calculation. Symbols show the
kind of precipitation, either snow
or rain.
The Weather Bureau considers a
temperature forecast accurate only
when it is within 7 degrees F. OF
the actual temperature in summer,
within 9 degrees in spring and
autumn, and within II degrees in
winter. Predictions concerning
rain or snow are rated as correct
only when proved to be SO by the
official gauges at the station.
Hardest Task
The Weatherman's hardest task
is forecasting local precipitation,
such as thundershowers and OF
course, snow flurries. To hand out
forecast that will be reasonably
right, he has to have detailed
knowledge of how mixed air and
water behave, the effects of vapor
pressure and relative humidity,
and the influence of altitude upon
air conditions.
Forecasting Of weather, far from
being guesswork any more. is
daily becoming more accurate,
thanks to new inventions; new ma
chimes, tried and proven theories
At the Weather Bureau many ano
varied are the instruments fo1
gauging wind, rain, heat, cold, etc
There is the rain gauge, which
catches rain in its open top, ano
drains it into a bucket inside the
gauge. When the bucket receives
1-10Oth of an inch of rain it dip:
and pours the rain into the con
tainer below. The movement also
operates an electrical machine, o.
instrument, which records thu
rainfall.
Other Gadgets
Then there is likely to be a Rob
inson-type thermometer for measur
ing wind speed and the anemo
graph for recording it. Another
gadget catches and absorbs hea
whenever the sun shines, and this
too, is recorded. Also close a
hand is whirling type Of wet-and
dry bulb hygrometer, or psychro
meter, which measures humidity
etc.
The science Of meteorology goe!
back to the days of Aristotle a
least, for that gentleman, although
he could only guess, wrote a bool
on the subject. Facts were no
Learned however, until the Their.
| MON eter and barom eter were in