Technical Manual: Meteorology (March 7, 1942)

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with his back

sure on the left is

t front is lower than

Southern Hemi-

the left and the

ht rear.

Milham, published by the Macmillan

ublisher)

40.

nced

n the

ery

ndi-

he

visi-

to

ht

ics

Chem-

nsity,

drift

.

be

ore

t be

lities.

actors

ation,

ding

ure

ssure

with

e—

ng and nearly

ass motions

o be determined

and force or pressure.

nt in chemical

e of the earth

movement in suc-

. This turbulence

h; it is greater

pronounced over

s caused in part

ss by checking

ve break over it

the air out of its

ies. Obstacles such

and also cause

five or six times

th altitude. In

t twice that at

lete mixing of

a gas or smoke cloud

s designated as

air moves from

nd.

mediate points

, northeast, east,

. However, in mili-

basis

s 16

om the

such

espec-

pro-

ery

d"

e-

eadily

r.

ction,

n-

en

ng cases. The wind

9y2 inches long. One

e ground; the others

sembled. The sup-

a 2-joint support.

nches high.

osed at one end and

being coincident with

a brass ring

m-

ed

on

able

x-

ximate

or any

air

e

ot,

on

perat-

ared

rs.

uilt

heel

sliding

ar-

ecording

ns of

oth

acing

ctedly

eter

have

of the

ch

n-

e

verted

(For

iprocal of 0.037 is

ur; hence, meters per

d velocity varies

s the mean of the

earest mile per hour.

h the anemometer

n the field. This can

nstrument case:

elicate instru-

d in the field with

nstrument must

accurate read-

mom-

t

des

ed in

ocity in miles per

ter. A screw on the

he speed dial and

e. To operate, turn

he speed dial. Hold

obstruct the wind

nstantaneous values

surement is re-

d velocity the mean

iod of approximately

developed to

anemometer used

permanently in-

ot applicable for

ent or semiperma-

orology" by

ind velocity

example is the

sed

ntrac-

sed in

ng to

t of

hat

ed

mum

eter as

y

apidly.

e.

cated

on a

ans-

elocity of cloud

movement of high

n. Certain cloud

he expectancy of

Observation of

n are therefore

velocity of mo-

herwise, clouds are

thunderstorms.

o the observer from

d in tenths of the

ms are used: clear,

%0 covered with

d; while cloudy

cloud.

d on their form

classifications and

Atlas (1932). The

ecorded in meteoro-

four groups:

s, none of which

-

n

d of

owish

n

m-

ment

or

rtion).

-

om all

ud

t

ation.

,

ces.

m

feet.

aped

ently

pments

per

pe of

cumulus below (at left).

cumulonimbus.

ith

s.

make

d for

ns

asses

n

s, and

often

s,

place

e air.

to

004

p into

il

now.

ugh

its

infall

meas-

urement

tion

sts

d rim

exact

into

e outer

the

receiver.

e depth

be is determined by

. Since measurements

pitation is determined

ght in the outer

ylinder have been

g tube

o in-

average

water

eas-

e meas-

ches

f

about

tely

era-

ist,

y be-

n of

on

ctor of

per

ty

re were

per-

e

given

can

n

me

y the

does

, or

mined

wn

al

a

of

covered

to be

s

meter,

bulb

e

between

ure in

eter.

ent

reads

bulb thermometer approximates relative

mass and is

nd exerts a downward

ng to the limits of

e atmospheric pressure

e pressure (as in

there were no

pressure would be

ot the case, however;

same level and is also

s necessary to have

tmosphere and its

mercurial barometer

essentially of a

mercury, and inverted

he whole is inclosed

e top, exposing the

er are provided for

reading certain

for instrumental

nto pressure at mean

idless and operates

box about iy2 inches

ver with corrugated

psing by a strong

is pressed together

ure decreases, the

slightly. These

s attached to a pointer

responding to the

rate than the mer-

heapness, and

a conven-

, particularly for

sage gives latest

and temperature.

code which should be

ne line of letters

cal

on.

r

ry;

wo

hun-

whole

as

f the

a basis

ures

he

wind is limited,

nd vegetation in

re continuously

ring periods of calm,

on account of

pon friendly troops,

on areas within

us state, are ma-

irritant candles

wind must be such

nto any portion

n applies when

to friendly troops.

n distant areas, the

eclude use of

ability of such winds.

ortars, projectors,

ot be considered

n the other hand,

clouds apart and

er the wind ve-

the shorter the

s. With high wind

t groups of men

and escape the

nd is requisite

c-

ss

ps in

eening.

nated area

ss than 500 yards

oser than 1,OOO

mperature of air

ime consumed

wind edge of a

ous distances

If the pre-

reduced.

safe distance

these lines from

c-

the

es a

rvation of the travel

a lateral spread

tance traveled to as

of gas or smoke

an line of wind

long the path of

candles.

f 6 miles on each side of

nt (E—E').

the lines E—1 and E'—1'

of 6 miles.

f 360 mils (20°) with the

safety angles.

f 270 mils (15°) with the

les of spread.

, gives the wind limits for

through 0 (the point of

and between the lines 0—3 and

tion must be postponed.

°)

egarded as danger-

or cloud attacks

must be established.

owing in any

ovided the area

o distance from

stard gas or other

tions,

th re-

re-

le

opera-

nder,

city 3 to 12 mph).

ach side of

and the target.

dge of the target

ines for a distance

(20°) with

es.

5°) with the

d.

limits for the

the friendly

— 3', it is a suitable

hemical

rds.

vailing

ned

ature is. an im-

cant agents, since

developed by the

given off by these

s may result; and

y injure anyone

er without rising

cals.

ccelerate the dissi-

r near the ground

he surface air which

currents will

iluted. Such cur-

er dry or plowed

of low tempera-

is no tendency

temperatures

nerally unfavorable

the day, especially

ble.

screening smokes

ncerned. The

clouds of non-

ver a limited area

he topography or

rows colder

aces of lower

se pockets of cold

e experienced. But

er hour, cold air

other points, thus

ncy of surface

will cause such

s of toxic agents.

ent can be at-

ced, however,

hut off sun rays

t. A clear, hot

ch cause rapid rise

en, is unfavor-

s

d of

-

-

of

shing

me

ordi-

dro-

e-

har-

sh

r

es

d

e-

ring

in

cloud

hey

ex-

end

hus

mp

owing

since

ir

ith

or-

ntity

vertical air

le effect on chemical

ause gas clouds

roops. These cur-

and they tend to

s downward, thus

h where it is most

h pressure areas.

cation of the effects

ts:

e of HS and CNS.

se of HS, this agent is more

al

ned

States

d in

be

dict-

re not

ecasts

must

cal

weather

om

nd the

pheric

nflu-

two

hief

for

tant

ese

g large

the

cated

s

alled

same

ing on the isobars

tral pressure averages

ust under 30 to below

oval in form, the ratio

of the longer axis

low in a counter-

angle with the

uadrant where it

hwest quadrant where

ements about a typical low.

sually moderate;

epresent cloudy

m cloud area mostly

precipitation falls

d area is usually

ds so that whenever

the result.

e isotherms or lines

There is a marked

the low pressure area

drop

ortherly

haped

along

orth-

n

line

ng rapidly as one

artment of Com-

r information—be-

y is still good for

ollowing may be

of weather map as now

ap is the old wind

rm air which is

a cold front.

esult is called

pical) low or

dying depression

ws little tendency

the warm or the cold

ravel in much

paragraph 24. The

of the warm sector

h barometric

hich turn clock-

wn by figure 24.

a, wind velocity,

clouds are seen

mation may

miles in diameter,

are often irregular

ighs instead of a

m however is the

heast-southwest,

pressure averages

rom slightly over

the isobars

erages from 20° to

re it averages from

alms

is a

essure

mpera-

he

udying any

are near enough to

se will sometimes

dominating forma-

. For example,

high may affect

ements about a typical high.

northeast or

ection.—

and or sea. They

erally from west to

avel southeast, some-

leave

y

m day

e

outh.

st

st

nd

of

are

orida,

ty.

ain-

to

ne

low

g

drifting

re

eed in

ay in

ases.

to

f

he northwest or

east.

or a day or

umed that it will

s per day in winter.

ween lows, usually

ather Bureau,

shed the following

- which are valuable

e southeast and a

e a storm develop-

eneral.

to the left of a

in to develop in the

torms that develop

ollowed by clearing

are of two types:

wly and storm

extreme southern

of an extensive

de intervening area

tures.

ward faster than

outh and southwest

m will form southwest

moves faster than

outheastward do

rve to the north-

as a rule, and care

st and northwest

orm, but slight

velopment of the

tortn indicate

nary.

oves to the left of

st

tatioh

nd

th-

uickly

ctions

on

will

to be

s as

25

s.

may

ghs

n. The

together.

place

ing,

for

ds

nd

cipi-

he

—The rules

nsideration of a

5. It will be noted

nts about the high

ral, the outline

s are explained in

ecast is to be

to show this position

under the influ-

his low will travel

d with the same

. From the map of

veled approximately

in the same

be a little northeast

may be expected

st to strong north-

g northwest

icipated.

e and that the

air from the south

eing taken by dry,

Arsenal on

ch colder, and clear.

—The follow-

s, and forecasts are

the daily forecast

ON

N, D. O.

AIRPORT OFFICE: Washington

1442

LEPHONE: WEather 1212

d by partly cloudy and

t with lowest temperature

y; fresh northwest winds today.

much cooler in west portion,

owers on the coast this morning;

ay fair and quite cool; fresh

inds on the bay and coast today.

owers in the interior today

and colder tonight; Wednesday

oday and tonight; Wednes-

ollowed by mostly cloudy

nesday fair and quite cool.

ning, followed by cloudy

air and quite cool.

hat colder today and to-

Wednesday fair.

h light showers in the

dnesday fair.

Ohio Valley, and Ten-

ss in the Washington forecast

f showers in the mountains

s Wednesday. It will be much

hifting to fresh to strong

and over extreme south portion

ne, to Block Island, R. I.,

lock Island, R. I., to Delaware

g rapidly

astward over the

perature reached

na and Illinois.

over most of the

Gulf States.

h Pacific States.

several

70 of those sta-

tion and velocity,

tation, and other

of different

tions indicate

n the boxes to

points of equal

rm and passes

line is labeled

and below the

elative positions

del." Occasion-

of some of the

s is heavily

ing at 1: 30 a. m.,

dicate a

re. Figures

ro.

"visibility"

more, the figures

and ceiling

ates the amount

is 2 or 3 tenths

ths, or completely

he current state

asic symbols for

derstorm. A

itation is falling or

he frequently used symbols

ght fog; O smoke; .}£] snow

st storm; = fog, sky not dis-

mittent light rain; >)«>{< con-

ers; | \ thunderstorm with

n, for example, a • represents

and a dot = represent rain and

not at time of observation."

rcle in the direction from

ft show the force of the wind

wo units of force and each half

, a wind blowing from the east

d be described as an "east

d, force 5." The adjacent table

velocity equivalents in miles

more complete and detailed

es. Inquiries should be

ngton, D. C."

g Sundays and holidays) is

Sundays, is $3.00 a year, or 25

ey order) to "Superintendent

s called a "front." Important

of a front. The half circle and

ymbols to indicate the classifica-

he boundary of relatively cold

d by warmer air of tropical

atively warm air advancing

is called a "warm front." The

ont is called an "occluded front."

little tendency at the time of

he cold air areas is called a "sta-

how their direction of

w barometric pressure.

dicate their

otes the polar

s. The letter

om southerly

nd "P" show

. The letters

warmer (W)

asses are

es from one type

mposed upon

perior (very

res-

000

-

i-

uals 1

92

1,000

scale

er-

:

millibars.

illibars.

eather reports

be the case in the

nd change and

d, by use of a pocket

ea

er goes

s pos-

eter

ation

er

of

arometer

gy.

McGraw-Hill Book

e Study of Air Mass

of North Amer-

rological t

, New York, N. Y.

New York, N. Y.

ilkins Co.,

ing in the United

D. C.

Maps may be ob-

ngon, D. C., at the

60 a year, 30 cents

cents a month.

(15).