TM 11-6660-218-12
(5) Record, in the right column, the time
STANDBY. Read the psychrometer in
each reference is reached from the con-
the baseline check set; first the wet bulb
trol recorder tape as it becomes available
temperature reading, then the dry bulb
during the flight.
temperature.
f. Preparation of Radiosonde Data Form DA
Note. The radiosonde set is left in the base-
Form 4197.
line check set until the validity of the baseline
is determined.
(1) Enter the following information in the
appropriate space on the form:
(6) Verify the temperature readings with the
(a) Station location.
temperature and relative humidity traces
(b) Flight number.
from the Frequency-Recorder Time
(c) Release time.
graph; use Computer CP223C/UM and
(d) Baroswitch serial number.
the following criteria:
(e) Computer.
(a) The 25 centigrade value must fall be-
(f) Checker.
tween 66.5 and 68.9 ordinates when
(2) The baseline check observations are en-
Thermistor ML-419/AMT-4 is used,
tered in the spaces opposite the words
and the relative humidity must be be-
BASELINE CHECK DATA, columns 1
tween 20 and 70 %. If the temperature
through 6.
or humidity traces do not fall within
the prescribed criteria, install a new
(3) The surface observational release is en-
temperature or humidity element, or
tered in the spaces opposite the words
both, and prepare for a new baseline
RELEASE DATA, columns 1 through 6.
check.
(4) Values for pressure, temperatures, and
(b) When the baseline check is valid, the
humidity aloft are entered as the data is
radiosonde set is removed from the
evaluated.
baseline check set. The baseline selec-
g. Selection of a Sounding Balloon.
tor switch is placed at TEMP and the
(1) The bursting altitude of a sounding bal-
power, the fan, the heater, and light
loon depends on conditioning, inflation
switches are turned to OFF.
procedure, and the type of balloon.
e. Preparation of Pressure Time Chart DA
(2) High altitude sounding balloons weigh
Form 8959.
1,000 to 1,200 grams and burst near an
(1) Enter the following information in the
altitude of 32,000 meters.
appropriate spaces on the form:
(3) Fast rising sounding balloons rise to
altitudes of 32,000 meters at a rate of
(a) Station location.
approximately 500 meters per minute.
(b) Flight number.
(4) Sounding balloons, at night, will nor-
(c) Release time.
mally burst at lower altitudes. Bursting
(d) Baroswitch serial number.
altitudes are with respect to sea level.
(e) Computer.
(5) Conditioning of sounding balloons before
( f ) Checker.
inflation is necessary to assure maximum
bursting altitude.
(2) The contact number which corresponds
(6) Sounding balloons in storage and exposed
to the surface pressure is entered in the
to relatively low temperatures lose elas-
bottom box of the left column, and the
ticity. Neoprene sounding balloons used
surface pressure is entered in the center
without conditioning will result in pre-
column.
mature burst.
(3) In the left column, cross out the num-
bered reference contacts lower than the
Note
contact which represents the surface
Balloons less than 1 year old need no
pressure.
conditioning. Exposure to room tem-
perature (21 C) for 24 hours is all
(4) The pressure for each reference contact
that is required.
number in the left column is read from
the radiosonde pressure calibration chart
(7) To insure maximum bursting altitude,
to the nearest whole millibar and entered
all sounding balloons will be conditioned
in the center column.
as described in paragraph 32.
3-3
Change 8
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