(2) Enter the densities for the remaining

plotted at the intersections of the hori-

zones, obtained from Chart ML-574A/

zontal and vertical lines.

UM, in column 1 opposite the appropriate

If the wind is from the west, select an

zone number on DA Form 4450.

origin at an intersection near the left

(3) After the required weighted densities

edge of the plotting board. If the wind is

have been determined and recorded, ob-

from the east, move to the right for the

tain the ballistic density values for each

origin so plots will not fall off the plot-

line by adding the weighted densities of

ting board.

each columns 1 through 15.

Center Scale ML-577/UM over the ori-

(4) Record these sums in the appropriate

gins for lines 1 through 15.

space under the line number.

Determine zone-weighted windspeeds

with the artillery tables, and plot the

weighted values with Scale ML-577~UM

1 ( * ) requires the plotting of a pressure time curve

and procedures given in *9h *(1) through

to establish the time at which the radiosonde set

(12) above.

reached the standard heights. Rawin DA Form

Complete the ballistic wind plot and

4469 is then completed as follows:

measure the ballistic wind direction and

(1) The pressure at the top of each zone,

speed. Record the data in columns 9 and

from Chart ML-574A/UM, is entered in

10 of DA Form 4469.

column 2.

(2) Time value, from the pressure time

curve, is entered in column 3, opposite

a. *The radiosonde data sheet *is completed when

each zone number.

the information obtained from the radiosonde re-

corder is entered on DA Form 4197.

corder tape is entered in columns 4 and 5.

the elevation angle for each standard

metro message is determined by use of the infor-

height, is determined from artillery ta-

mation obtained from DA Form 4197 and Chart

bles and entered in column 6.

ML574A/UM. The altitude pressure density is

measured with the zone height scale, which is

dures described in paragraph *3-4g.*

graduated in meters and indicates the thickness of

the standard artillery zones.

enter the distance traveled in each zone

(1) Plot the significant data from DA Form

in column 7.

4197 for each significant level on Chart

ML-574A/UM successive legs for a 15-

data in column 8.

Iine message.

(2) Compute ballistic temperature, using

use Scale ML-577/UM, and enter zone

Chart MG574A/UM with the artillery

wind directions to the nearest 10 roils in

tables, and enter the data on DA Form

column 9.

4450.

(3) Report ballistic temperatures as percents

enter the data in column 10.

of standards, and enter a check in the

(10) Enter the surface wind measurement;

type of message being prepared.

use the hand velometer and enter the

(4) Complete ballistic temperatures for lines

data in columns 11 and 12.

1 through 15 and enter the sum of the

ballistic values on DA Form 4450.

3-6. Sound-Ranging procedures

The standard meteorological conditions for

c. *Ballistic densities *for all meteorological mes-

sound-ranging computations are based on a height

sages are computed and entered on DA Form 4450.

of 200 meters above the surface level, with a zero

The densities are read from Chart ML-574A/UM

windspeed, at 100 Centigrade. Speed of sound

and recorded on this form.

under these conditions is 337.6 meters per second.

(1) Enter the surface density in column 1,

a. *Effective temperature *for sound ranging is

after checking the block marked DEN-

determined from measurements of temperature

SITY GM/M3, to indicate the form iS

and relative humidity.

being used to compute density.

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