NATIONAL BUREAU OF STANDARDS REPORT

2251

EVALUATION OF THERMOSCREEN TYPE NAX-1-46

by

H . R . Mart in

R. S. Dill

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing of

the divisions and sections engaged in technical work. In general, each section is engaged in special*

ized research, development, and engineering in the field indicated by its title. A Brief description

of the activities, and of the resultant reports and publications, appears on the inside of the back

cover of this report.

Electricity. Resistance Measurements. Inductance and Capacitance. Electrical Instruments. Magnetic Measurements. Applied Electricity. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Gage.

Heat and Power. Temperature Measurements. Thermodynamics. Cryogenics. Engines and

Lubrication. Engine Fuels. Cryogenic Engineering.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State

Physics. Electron Physics. Atomic Physics. Neutron Measurements. Infrared Spectroscopy.

Nuclear Physics. Radioactivity. X-Rays. Betatron. Nucleonic Instrumentation. Radiological Equipment. Atomic Energy Commission Instruments Branch.

Chemistry. Organic Coatings. Surface Cherpistry. Organic Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chemistry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Aerodynamics. Engineering Mechanics. Hydraulics. Mass. Capacity, Density, and Fluid Meters. Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifi- cations. Polymer Structure. Organic Plastics. Dental Research.

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Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure. Chemistry of Mineral Products.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Machine

Development.

Electronics. Engineering Electronics. Electron Tubes. Electronic Computers. Electronic

Instrumentation.

Radio Propagation. Upper Atmosphere Research. Ionospheric Research. Regular Propagation Services. Frequency Utilization Research. Tropospheric Propagation Research. High

Frequency Standards. Microwave Standards.

Ordnance Development. These three divisions are engaged in a broad program of research

Electromechanical Ordnance, and development in advanced ordnance. Activities include

Ordnance Electronics. basic and applied research, engineering, pilot production, field testing, and evaluation of a wide variety of ordnance materiel. Special skills and facilities of other

NBS divisions also contribute to this program. The activity is sponsored by the Department of

Defense.

Missile Development. Missile research and development: engineering, dynamics, intelligence,

instrumentation, evaluation. Combustion in jet engines. These activities are sponsored by the

Department of Defense. • Office of Basic Instrumentation • Office of Weights and Measures.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

1003-20-4713 February 5, 1953. 2251

EVALUATION OF THERMOSCREEN TYPE NAX-1-46

by

Ho R. Martin

Ro So Dill

Heating and Air Conditioning Section

Building Technology Division

To

Bureau of Aeronautics

Department of the Navy

Washington 25, D, C.

The publication, reprint

unless permission Isobti 25.D.C, Such permiss

cal ly prepared If that i

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 201 5.

irt, Is prohibited

rds, Washington

has been speclflfor Its own use,

EVALUATION OF THERMOSCREEN TYPE NAX-1-46

by

Ho Ro Martin

Ro So Dill

I. INTRODUCTION

The Weather Bureau type of wooden thermoscreen has

served its purpose for many years and its continued use

is probable particularly for some shor.fe installations,

where low cost Sis a factor or whe^e electric power is not

available 0 For shipboard use, however, it has been realized for some time that a different thermoscreen which

should be smaller, less conspicuous, more convenient to

use, more durable and, if possible, capable of yielding

more accurate weather data was desirable * Also, to reduce

cost, the number of spare parts and storage space, it was

desirable that the same type of thermoscreen should serve

both on board ship and ashore 0

In preparation for formulating a new design, several

shapes and sizes of thermoscreens were considered and several prototypes were made and tried in field experiments

along with two wooden thermoscreens with designs accepted

by the Weather Bureau 0 The size and, to a degree, the

shape were determined by the dimension of the instruments

which the thermoscreen had to accommodate to comply with

Bureau of Aeronautics requirement s „ As a result of the

experience gained, the Type NAX-1-46 thermoscreen was designed and six specimens were constructed on contract according to drawings and specifications prepared at this

Bureau,, Of these six, one was retained for further testing

and the other five were delivered to various ships and shore

stations for trial*

The performance of the Type NAX-1-46 thermoscreen,

observed during these tests, was compared with that of the

Large Wooden (Weather Bureau Type) thermoscreen which had

proved best of those previously tested in point of accuracy

of results*

II* SAMPLE AND TEST APPARATUS

The specimen NAX-1-46 thermoscreen retained at the

National Bureau of 'Standards is shown in Figure 1* It is

described in drawings already submitted to the Bureau of

Aeronautics* The instrument space in this thermoscreen is

about 20 inches wide, 21 inches high and 12 inches deep from

front to back* The instrument space is surrounded by two

annular air spaces formed by three metal walls or shells and

these spaces as well as the instrument space are copiously

ventilated by the fan at the top which draws air into the

bottom and upward through the thermoscreen*

For tests, the specimen was set up in an open space on

the Bureau grounds as shown in Figure 2. This photograph

also shows the anemometer used for wind measurement and the

four devices provided for evaluating ambient conditions.

For convenience these devices were called ”sensory elements”

and each such element consisted of a horizontal tube containing a dry thermocouple and a thermocouple fitted with a wick,

which was kept wet to serve the same purpose as the wet bulb

thermometer in a psychrometer . A motor-driven blower drew

air through the tube and around the thermocouples when the

device was in use and the emfs of the thermocouples were register

ed by the potentiometer, in the instrument shelter, shown in

Figure 3.

During the tests, the thermoscreen faced north and was

supported with its bottom about four feet above the ground

by a steel frame. The ^anemometer of the wind measuring set

was mounted on a mast about 12 feet high and its indicating

and recording instruments were also located in the instrument

shelter.

Temperatures were measured with calibrated copper-constantan thermocouples in conjunction with the potentiometer,

mentioned above, which was a Brown 16-point recording instrument. For air temperature measurement, the thermocouples in

the sensory elements were fitted into small bronze spheres

about 3/l6-inch in diameter to afford some stabilization of

the readings and these balls were coated with aluminum paint

to minimize radiation effects.

The thermocouples were so connected that the differences between the emf of each thermocouple and that of thermocouple No. 15, in the west sensory element, were recorded on

a strip chart at four minute intervals. This permitted the

use of an open scale on which readings could be made readily

with a precision equivalent to ± 0 o l°F„ The temperature

differences reported herein are therefore the differences

between the temperatures at various points and the so-called

"true 7 ' temperature inside of the reference sensory element.

A plus sign indicates that the temperature- at. any point was

greater than that in the reference sensory element, whereas

a negative sigh indicated the reverse. For convenience this

difference is called the "error” or the "temperature difference”.

All leads from the thermo junctions to the recorder were

shielded to minimize the effects of stray electrical fields.

Location of the thermocouples are given in detail in Table 1.

The shelter for the recording equipment was approximately 4 feet square and $ feet in height with well-insulated

walls and door. A small window in the back of the shelter

- 3 -

was of double glass and faced north to minimize heat gain

or loss. The temperature within the shelter was regulated

by Mercoid controls in conjunction with suitable heating

and air conditioning equipment to maintain the inside

temperature at about 70°F. The power supply to the equipment was brought into this shelter through shielded and

grounded cables*

't ^ Data on solar intensity were obtained from the U* S.

Weather Bureau pyroheliometer located at 24th and M Streets,

N* W* , a distance of some two miles from the site of these

tests* Solar intensity was measured and reported in V, Langleys o The Langley is defined as one gram calorie of

energy per square centimeter received by a horizontal surface *

The anemometer of the wind measuring set, shown in

Figure 2, was connected by special circuit so that the

wind indications were recorded by the potentiometer mechanism

on the same chart with the temperature data* This arrangement was calibrated in the Bureau *s wind tunnel and found

to require a correction of about plus 1-1/2 miles per hour

at all speeds in the range of interest

,

III* PROCEDURE AMD OBSERVATIONS

Since the error in air temperature measurements depends

on sun intensity and wind, most of the tests were made during

the day and, for comparison of thermoscreens, data were selected which were obtained on days of strong sun and little wind.

The average values of temperature, temperature differences

wind speed and solar intensity for each full hour of operation were considered an observation and the observations are

averaged and summarized in Tables 2 and 3®

In Table 2, the data from the test of the Large Wooden

Thermoscreen are included with those from the test of the

Type NAX-1-46 thermoscreen for comparison while in Table 3

more detailed data on the Type NAX-1-46 thermoscreen are given

The same data were plotted in Figures 4, 5 and 6 for convenience, In Tables 4, 5 and 6, instrument readings are record

ed which were selected between the same hours of the day to

afford a comparison of the NAX-1-46 with the Large Wooden

Thermoscreen* This was done to lessen the error due to differ

ences in the altitude of the sun so that the two thermoscreens

could be compared under as near similar circumstances as possible.

IV* RESULTS AND DISCUSSION

Field tests of thermoscreens are necessary because sunlight, wind and sky radiation cannot be reliably simulated

in the laboratory. Preliminary tests can be conducted in a

laboratory to avoid waiting for suitable weather and infra

- 4

-

red electric lamps can be used to simulate radiant heat

from the sun but the results must be considered indicative

only and should not be used to evaluate the performance of

thermoscreens. Laboratory evaluation of thermoscreens may

become feasible if and when knowledge of the subject is

sufficient to permit it.

Any object exposed to sunlight assumes a temperature

above that of the ambient air and the temperature within

an enclosure like a thermoscreen depends on energy reception and heat dissipation which is caused chiefly by . ventilation. An objective of thermoscreen design is to

provide sufficient ventilation so that the instruments

within it will indicate or record true ambient air conditions within an acceptable tolerance. For the wooden thermoscreen, natural wind has been relied upon to furnish ventilation; in models under development, including the type

NAX-1-46, motor driven fans or blowers are being used.

Any instrument used to determine or evaluate outdoor

air conditions is subject to the same difficulty and in this

work it was met by means of the sensing elements mentioned

in the Introduction and discussed in the Report on Thermoscreen Development Project submitted December 1$, 1950.

When exposed to sunlight, there is no doubt a difference

between the temperature indicated by this instrument and

the true air temperature, despite the large ventilating

rate provided. Also, the magnitude of this difference is

not known but it is undoubtedly small and it is muoit smaller than the short-time fluctuations in ambient air temperature indicated by the thermocouples. These short time

fluctuations act to prevent precision and accuracy in air

temperature measurement. In the present work the potentiometer reading was observed to wander over a range of one to

three degrees in a period of -four minutes or less. It is evident that a definition is needed and an average over some

time interval must be used since the temperature is always

changing. Perhaps a standard thermocouple fitted with a

specified mass of metal to serve as heat capacity would be

a practical solution to the problem. Some experimentation

is essential but, as a first estimate, an arrangement for

which the temperature indication does not change by more

than one degree in five minutes in calm weather might be

suitable

Information on the essential accuracy in air temperature measurement for weather forecasting purposes has been

sought in the literature and in conferences with authorities

in that field and the indications are that the accuracy being

currently attained is not known and that required has not

been established. At sea or on the coast or with steady winds,

the momentary fluctations in air temperature may be smaller

or even insignificant but, as stated above, the indicated

variations under the test conditions were sometimes as much

as three degrees in four minutes. The data in Tables A , 5 and 6 show that the error was usually greater than 0.5 degree F and less than 1.0 degree F under low wind and intense

sunlight conditions for either the Large Wooden or the

NAX-1-46 thermoscreen. Based on this, an accuracy of one

degree F is suggested as a criterion for extreme conditions

such as those of the tests. Accuracy better than one degree F can be expected with either thermoscreen when it is

in use on a ship under way since the ship’s motion will

create relative wind except in the rare case when she is

proceeding in the same direction and speed as the wind.

Also, accuracy better than one degree F for low wind and

strong sun conditions may be a justifiable requirement in

the future (1) when the art of weather forecasting has advanced sufficiently to require it and (2) when instruments

are made available to attain it.

The data in the accompanying charts and tables show

that either the Large Wooden or the type NAX-1-46 thermoscreen yielded data with an error of less than one degree F

in the great majority of the tests. It was unfortunate that,

during these tests , the maximum sun load usually occurred simultaneously with the maximum wind. If this had not been so,

a better correlation between either error and wind or error

and sun load could have been obtained. The indications were

that the error in the temperature measurements with the

Type NAX-1-46 thermoscreen were somewhat less than those

occurring with the Large Wooden thermoscreen. The Type

NAX-1-46 is therefore acceptable from the standpoint of accuracy and will be so as long as the results obtained with

the Large Wooden therm oscreen are considered adequate. The

question of its adoption for general use devolves, therefore,

upon its conveniences, portability, adaptability to shore

and shipboard installation, cost, and appearance.

In Figure 5, the number at each plotted point is the

number of observations averaged to obtain that point. The

results shown indicate that with the NAX-1-46 thermoscreen

the error tended to be independent of the wind speed whereas

with the Large Wooden thermoscreen the Srror, in general,

increased as the wind speed decreased. Unfortunately no

observations were obtained at wind speeds less than 1.5 mph

However, since the NAX-1-46 thermoscreen w$s provided with

forced ventilation, it is believed that the error would not

have increased significantly at the lower wind speeds.

Although no measurements were made of the intensity of

the radiation incident on the vertical surfaces of the

thermoscreens , it was recognized that this appeared to be

an important factor. In the absence of such measurements,

the observations were separated into groups in accordance
.

• v
- 6 - with the hour of the day in which the observations were made.

The average values for these groups of observations are plotted in Figure 6. The number at ‘ea~ch plotted point is the

average of the number of observations averaged to obtain that

point

The results shown in Figure 6 indicate that there was

very little difference between the errors obtained' with the

two types of thermoscreens for the same time of day. Assuming that the intensity of incident solar radiation on similarly oriented vertical surfaces at a given time of day and year

was proportional to the observed intensity of radiatibn incident at the same time on a horizontal surface, the intensity

of radiation on the vertical surfaces of NAX-1-46 thermoscreen

was greater than that for the targe Wooden one 0 However, the

data show that the wind speed was also greater during the

tests of NAX-1-46 although as previously stated the performance of this unit was probably independent of wind speed.

It should be noted that the error for the NAX-1-46

thermoscreen was a minimum at about midday when the intensity of the radiation incident on the vertical surfaces was

probably a minimum for the period in which the observations

were made. Later in the afternpon when the intensity of the

radiation incident on a horizontal surface had decreased,

that on the west vertical surface had increased, t hereby”"an -- creasing the error. In the case of the NAX-l-4o thermoscreen

there was little change in the average wind speed, consequently, the increase in the error must be attributed to an increase in the intensity of the radiation incident on the west

vertical surface. In the case of the Large Wooden thermoscreen the wind speed decreased 'in the afternoon as the intensity of the radiation incident on the west vertical surface increased, both of which contributed to the increase in

the error.

For this locality when these tests were made, it appears

that on clear days, the wind speed reached a maximum about

midday when the intensity of the solar radiation incident on

a horizontal surface also reached a maximum, and that on a vertical surface reached a minimum, for the time of year at

which these observations were made. The combined effect of

these factors results in a minimum error at about midday.

In the afternoon the decrease in the wind speed and the increase in the intehsity of radiation on a vertical surface

facing west, result in an increase in the error.

The basic construction of the Large Wooden Weather Bureau

thermoscreen was such that it would be impossible to correlate

the effect of solar radiation on the louvers of this unit with

the protective shields of NAX-l-46 , so, for this reason, the

evaluation of the units was primarily based on the end effect;

that is the error in the temperature of the air within the

instrument shelter.

- 7 - Temperature measurements were made in various parts of

the NAX-1-46 thermoscreen to determine the effects of solar

radiation and to provide information for further improvements

in thermoscreens with mechanically circulated air. The data

listed in Table 3 were taken between the hours of 10 A.M. and

4 P.M. EST. A vertical surface facing East during the months

of May and June would be expected to receive the same amount

of solar radiation at about $ A.M. as a similar vertical surface facing West at about 4 P.M. ; therefore the effect on

the eiast inner shield at <3 A.M. should be similar to that

on the Vest inner shield at 4 P.M. It was not possible to

make measurements in the test area

? however, during the

earlier hours due to shading by buildings.

It will be noted in Table 3 that the temperature difference of the east inner shield (Column 1) was the greatest

in the morning whereas that on the West inner shield (Column 3)

was greatest in the afternoon. The air temperatures within

the instrument space taken 1 inch from the east inner shield

(Column 11) also showed the greatest temperature difference

in the morning and the error in the air temperature taken

towards the West center of the instrument space (Column 12,13)

was greatest in the afternoon. The changes in the inner

shield temperatures through the day and the corresponding

effects on the air temperature in the immediate region. indicate the necessity of providing more adequate thermal 'insulation and/or ventilation. During the tests, the mercury column

in the maximum thermometer separated several times and the

rider settled in the minimum thermometer apprently due to vibration communicated from the fan motor. Thin, sheet rubber

separators under the supports of these thermometers ended

these difficulties. Otherwise, continuous operation of the

Type NAX-1-46 thermoscreen in the field from November 7, 1951

to July 2$, 1952 without any other trouble indicated its

satisfactory mechanical durability.

Reports on field trials of the NAX-l -46 thermoscreen have

been received from the U. S. Naval Arctic Test Station, Point

Barrow, Alaska, dated 30 April 1952, and from the U. S. Naval

Air Station, Pensacola, Florida, dated 2 September 195?, Details can be obtained from these reports but, in general, the

only unfavorable finding from the Florida Station concerns

the durability of the hardware and the finish. If additional

thermoscreens of this type are to be procured, better enameling of the case and corrosion resistant hardware should be assured, T ri the tests under arctic conditions, vibration, snow

cloggin of the insect screen and freezing on the wet bulb sufficient to hinder manipulation were caused of trouble. The

vibration may have originated externally to the thermoscreen

since the writer of the report suggested use of a telephone

pole as a more stable mount. A precaution against vibration

originating within the thermoscreen, found during test at the

National Bureau of Standards, is described above. Snow clogging

- d - Qf the insect screens was not anticipated although obvious

after the facto A possible remedy would be to remove this

screen for arctic use to see if any snow entering the

thermoscreen would blow on through without harming the instruments. The electric heater installed in the water

reservoir was intended to prevent difficulty due to ice

formation on or about the wet bulb thermometer. It would

be interesting to know whether this heater was in proper

operation or not when the reported freezing occurred.

If so, some more effective preventive must be sought.

V. CONCLUSION

The type NAX-I-46 thermoscreen is considered to be

an improvement over others in common use in regard to size,

convenience, appearance and accuracy at low wind speeds.

It is not subject to splintering if struck by a missile

as a wooden structure would be. Tests of it are being

discontinued and efforts are now concentrated on development of a smaller thermoscreen which will make it possible

to read weather data from inside a protected shelter.

Figure 1, Thermoscreen NAX-1-4.6
>:


Figure 3. Interior View of Protective Shelter

Showing Recording Equipment,
4)

V9

<Y'Y «V
Table 1. Location of Thermocouples Used for Test

T.C. #1 -

T.C. #2 -

T.C. #3 -

T.C. #4 -

T.C. |-5 -

T.C. #6 -

T.C. #7 -

T.C. #g -

T.C. #9 -

T.C. #10-

<*

T.C. #11-

T.C. #12-

On inner (East) surface of inner aluminum shield

in instrument shelter, 6 inches down from top,

to left in Figure 1.

On inner (East) surface of inner aluminum shield

in instrument shelter, 6 inches up from bottom,

to left in Figure 1.

On inner (South) surface of inner aluminum shield

in instrument shelter, 6 inches down from top,

to back in Figure 1.

On inner (South) surface of inner aluminum shield

in instrument shelter, 6 inches up from bottom,

to back in Figure 1.

On inner (West) surface of inner aluminum shield

in instrument shelter, 6 inches down from top,

to right in Figure 1.

On inner (West) surface of inner aluminum shield

in instrument shelter, 6 inches up from bottom,

to right in Figure 1.

On outer (South) surface of middle aluminum shield

in instrument shelter, at center back in Figure 1.

On inner (South) surface of outer aluminum shield

of instrument shelter, at center back in Figure 1.

In space (East side) within instrument shelter

near max-min thermometers, 10 inches up from bottom and 1 inch in from inner shield, to left in

Figure 1.

In space (West center) within instrument shelter

near Bourdon element , 4 inches up from bottom and

6 Inches in from inner aluminum shield, to right

in Figure 1.

In space (West center) within Instrument shelter,

2 inches down from top and 6 inches in from inner

aluminum shield, to right in Figure 1.

Wetted thermocouple consisting of 3/l6-inch diameter aluminum-painted bronze ball in sensory

element, about 6 feet south of unit in Figure 2.

NBS
I
T.C. -#13 - Wetted thermocouple consisting of 13/32-inch

diameter aluminum-painted bronze ball in sensory element, about 6 feet west of unit in

Figure 2.

T.C. #14 - Wetted thermocouple consisting of 9/32-inch

diameter aluminum-painted bronze ball in

sensory element, about 6 feet east of unit

in Figure 2.

T.C. #15 - Thermocouple reference Junction (representing

“true” ambient air temperature) taken in West

sensory unit.

T.C. #16 - Air to melting ice temperature difference

taken in North sensory unit.
> •
Table 2. Test Data Tabulation

Thermo screen NAX-1-46

Number

of , observations 1 1

i

Wind speed^ Average incident

1 solar radiation

1 in Langleys/hour

i

i Average

, error4

Range i Average

i

i MPH

i

i MPH

i

« Deg F

2 ' 2.2 to 2.5 i 2.3 ' 62.9 » 0.45

i 7 , 2.5 to 2.9

i

i 2.6 , 73.1 .67

4

'

i 2.9 to 3.3

i

i 3.0

1 79.6

1 .60

9 « 3.3 to 4.0 i 3.6 ! 75.5 ' .S3

i 5 , 4.0 to 4.5

i

i 4.2 , 8U.8 , .72

7

’

1! 4.5 to 6.0 i

i 5.0 77.9

| .S3

5

*

i 6.0 to 7.5 i

i 6.4 • 89.0

i

! .62

Large Weather Bureau Thermoscreen

10

8

, 1.5 to 2.0 , 1.7 , 24.4 , 1.54

11 ! 2.0

I to 2.2 1

i 2.0 1

i 40.4 ' 0.97

i 12 i 2.2 to 2.5 « 2.3 ' 47.1 » 1.12

22

i

, 2.5 to 2.9 | 2.6 \ 54.9 ; 0.96

20 1 2.9

g to 3.3 1

| 3.0 '

i 60.6 1 .si

i 10 » 3.3 to 4.0 j 3.7 • 62.5 • .72

7 | 4.0 to 4.5 | 4.2 I 62.3 ! .54

11 ! 4.5

g to 6.0 1

i 4.S 'i 66.0 1 .46

i 0 i 6.0

8 to 7.5 '

i

i

i

Footnotes on following page.
V .

-

.

‘

"'< -m
4

1 An average of 15 readings were taken during each hour.

The number of hourly observations so averaged are

listed.

Averaged by planime tering a continuous wind speed vs.

time recording with an AM/UMQ-5 wind measuring set.

1 Average value of incident solar radiation on a horizontal surface in gm cal/( sq cm-hr).

^ Temperature difference between the average temperature

of the instrument shelter thermocouples* and that of

the reference “true *1 air temperature. A positive

value Indicates Instrument space temperatures higher

than “true" air.

*T.C. #9-10-11 as in Table 1 for NAX-1-46 and T.C. for the

large Weather Bureau thermoscreen as follows: In hygrothermograph between hair and Bourdon elements, near raax- mln thermometers near bulbs of sling psychrometer , and

centrally located in instrument shelter.

THERMOSCREEN NAX-1-46

Range of Hourly Average Values

Radiation

Wind

Ambient temperature

Relative humidity

56.6 to 92.9 Langleys/hour

2.3 to 7.5 mph

64.9 to 90.2 °F

30.0 to 69 .O percent

LARGE WEATHER BUREAU THERMOSCREEN

Range of Hourly Average Values

Radiation

Wind

Ambient temperature

Relative humidity

3.2 to £4.5 Langleys/hour

1.6 to 5*9 mph

67 .0 to S9.0 °F

43.0 to 94.0 percent

NBS

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o

o

_

_

CD

o cn

OO

roo

ojOo

tnO

CDOO

CDo

CDOOo

o

o

c

o

1

<2

p

o*

0> • • o 0 • • • •

2.9- 3.3 3.3- 4.0 4.0-4.

5 4.5- 6.0 60-7.5

WIND SPEED MPH

001

o

CD

o

in

o

o

to

o

OJ

o

WIND

SPEED

MPH



EASTERN

STANDARD

TIME

r

-H

>

X

x

m

o

|j

m

o

^

o

g

m

m

zz

zI

r>

i

a>

r~momzo

ff

ed,

in"|f

Urn 8 L

(9)

Av. temp. diff.

center middle

shield, south

(Av. of T.C. 7)

• (10)

1 Av. temp. diff.

1 center of outer

' shield, south

' (Av. of T.C. 8)

1.90 9.80 •

1.90 11.10

2.00 11.20

2.10 11.10

2.00 8.80

2.00 6.00

1.98 10.19

(19) (20)

ff., Av. temp, diff..

lory east wet sensory ' Avmax. temp.

av. element and av

' diff . among wet

13 (Av. of T.C. 14 1 sensory elements

of minus av . of 1 (av . of T.C.

) 12, 13 , 14) ' 12 , 13. 14)

-0.06 0.26

-0.03 .26

-0.10 .22

-0.18 .49

-0.28 • 52

-0.28 • 51

-0.12 0.34

NBS

Table 3- Tabulation of Air and Shield Temperature Differences, °F, from Tests on NAX-1-46

Eastern

standard

time

Number of

observations

a)

Av . temp. diff.

inner shield,

east (Av. of

T.C. 1 and 2 )

( 2 )

Av. temp. diff.

inner shield,

south (Av. of

T.C. 3 and 4)

( 3 ) Av. temp. diff.

inner shield,

vest (Av. of

T.C. 3 a-nd 6)

W

Av. temp. diff.

shields listed

(Av. of

T.C. 1 to, 6 ihc.)

(5)

Av. temp, diff.,

top to bottom,

inner shield

east (Av. of

T.C. 1 minus 2)

10 to 11 a.m. 7 1.29 0.25

1

' 0.77

i

0.77 0.13 0.21 0.02 0.12 1.90

- -r

9.80 •

11 to 12 a.m. 9 0.91 .25 ' .67 .61 .13 .19 .04 .12 1.90 n.io

12 to 1 p.m. 9 .71 39 ' .83

i

.64 .14 .18 .02 .11 2.00 11.20

i to 2 p.m. 7 • 75 .42 1.32

1

.83 .13 .19 .05 .12 2.10 n.io

2 to 3 P-»* 3 .86 .47 ' 1.61 98 , .11 -0.03 .18 .10 2.00 8.80

3 to 4 p.m. 4 1.09 00 4

' 2.72 1-53 .14 .47 -0.03 .19 2.00 6.00

Average 0.92 0.38 ' 1.13

1

0.81 0.13 0.20

a

0.03 0.12 1.98 10.19

Eastern

standard

time

Number of

observations:

(ID

Av. temp. diff.

air in shelter,

near max-min

(Av. of T.C. 9)

(12)

Av. temp. diff.

air in shelter,

near bourdon

tube (Av. of

T.C. 10)

’ U3)

1

' Av. temp. diff.

' air in shelter,

' 18" above

1 Bourdon tube

' (Av. of T.C. 11)

1

w

Av . of air

temp. diff.

listed (Av. of

T.C. 9. 10, 11)

(15)

Av . temp. diff.

air in shelter,

near max -min

and Bourdon

tube (Av. of

T.C . 9 minus 10)

(16)

Av. temp. diff.

air in shelter,

18° above

Bourdon tube and

Bourdon tube (Av

of T.C. 11

minus 10)

' (17)

1 At. temp, diff.,

'south vet sensor;

' element and av

' (AT. of T.C. 12

1 minus av. of

' 12. 13. 14)

(18)

Av. temp, diff.,

vest vet sensory

element and av.

(Av. of T.C. 13

minus av. of

12, 13, 14)

(19)

Av. temp. diff..

east vet sensory

element and av

(Av. of T.C. 14

minus av. of

12, 13. 14)

(20)

Av . max . temp

diff. among vet

sensory elements

(Av. of T.C.

12, 13. 14)

10 to 11 a.m. 7 0.93 0.55

1

0.55 0.68 0.38 0.00 0.14 -0.08 -0.06 0.26

11 to 12 a.m. 9 .76 .46

!

- 55 .59 .30 .09 • 13 -0.08 -0.03 .26

12 to 1 p.m. 9 -59 • 57 .71 .62 .02 .14 .10 -0.02 -0.10 .22

1 to 2 p.m. 7 .63 .63

;

.85 .70 .00 .22 .23 -0.01 -0.18 .49

2 to 3 P-“. • 3 .81 .89 1.10 .93 -0.08 .21 .23 .05 -0.28 .52

3 to 4 p.m. 4 • 75 1.07 1 1.45 I .09 -0.32 .38 .18 .06 -0.28 .51

Average 0.73 0.63 1 0.78

1

0.71 0.10 0.15 * 0.15

-0.03 -0.12 0.34

( 6 ) Av. temp, diff.,

top to bottom,

inner shield

south (Av. of

T.C. 3 minus 4)

(7)

Av. temp, diff.,

top to bottom,

inner shield

ve 8 1 (Av. of

T.C. 5 minus 6)

(8)

Av. temp. diff.

shields listed,

top to bottom

(At. ofT.oC l'

fcuiue

4, 5 inns

(9)

Av. temp. diff.

center middle

shield, south

(Av. of T.C. ?)

( 10 ) Av. temp. diff.

center of outer

shield, south

(Av. of T.C. 8)

<NBS>

Table 4

Thermoscreen Errors Observed Between 10:00 and 11:00 O’clock

NAX 1-46 Thermoscreen

1 Test No,

i

Langley Wind

hour ' MPH

i

Ambo

' op s

1

R 0 H 0 fo

'

1 Date

1

1

1

Error

op

6

1

i 73.1 \ 2.8 73.9 | 64

! 5-29-52

1

1 0.4

12 1 76c 7

1 4.2 75.4 ' 46 ! 5-23-52 1 .7

16 , 31.0 1 3*7 86.7 , 43 6-19-52

B

1 .9

17 75o

5 | 3.2 85.0

\ ; 6 - 17-52

1

1 .3

29 1 T7. 6

1 2.7 79.4 ! 62 * 6-15-52 1 .3

33 8 34 . 3 1 6 0 2 64.9

48 1 6-11-52 1 .9

36 1 $2 .1 | 4« 5 80.3

; 45

j 6-13-52

1

1 .9

Average 73.63 3.90 77.94 53.85 0.70

Large Wooden Thermoscreen

A

( 41.0

|

1 2.9 , 67

1

1 71

i

1 7-21-50

| 0.57

B

*

1 70.2 ' 4.2 ! 30 8

1 55 1 7-25-50 ' .53

C 1 66.6 1 3.0 , 72 1 67 1 7-27-50 , .61

1 D , 69.2 3.1 J 30

1

1 64

1

1 7-29-50 | .74

E

1

1 71.8 1 3.3 1 33 8

g 63 8

a 7-30-50 !1 .47

F 1 61.4 1 3.1 1 37 1 66 1 3-1-50 1 .69

1 G , 79.0 |

1 4.9 , 741

1 53

i

1 8- 4-50 | .27

H

1

1 79.0 '

| 3.3 19 73 8

g 53 0

j 3-6-50 '

1 .41

I 1 75.4 > 2.1 1 75 1 56 1 8- 7-50 , .63

1 J , 74.4 | 2.6 | 77

1

1 56

1

1 8- 8-50 j 1.10

L

1

1 59.2 1

1 2.9 11 30 !

| 70 1

g 3-31-50 1

g 0.74

M 1 46.2 1 2.3 1 77 1 94 1 9

- 10-50 1 .44

Average 66.11 3.18 77. 50 64. 41 0.60

Table 5

Thermoscreen Errors Observed Between 13:00 and 14:00 0

1

NAX 1-46 Thermoscreen

r clock

Test No,

Solar Inten„

Langley hour

Wind

MPH

Air Temp.

°F

R.H.

*

Date

Error

°F

1 75 o 5 3 80.7 43 5-25-52 0.$

9 85.

4 .73.5 34 5-27-52 .$

22 $4.4 3.0 $3 .$ 57 6-15-52 .7

34 $2 o $ 5.5 84.9 37 6-l$-52 .7

37 78.7 2.6 $6.0 57 6-16-52 .6

39 90*4 6.2 69.0 45 6-11-52 .6

42 74.9 4.9 90.1 34 6-19-52 .4

Average 81.74 4.22 $1.14 43. $ 0.66

2

3

4

5

6

7

3

9

10

11

12

13

14

15

16

Table 5 - continued

Large Wooden Thermo screen

Langley

hour

Wind

MPH

Amb

°F

R.H. *

Date Error

°F

33.5 2.0 71 62 7-21-50 0.31

73.1 4.5 32 49 7-25-50 . 55

73.4 2.9 73 54 7-27-50 .90

73.

8

3.0 35 52 7-29-50 .34

72.5 3.2 37 54 7-30-50 .66

19.8 2.9 35 30 3-1-50 .97

78.3 4.5 73 47 3-4-50 .50

53.0 5.9 30 50 3-6-50 .46

58.5 2.6 73 50 3-7-50 1.02

77.4 2.3 32 47 3-3-50 1.43

65.6 2.1 34 51 3-30-50 1.05

56.2 3.3 33 64 3-31-50 .70

50.4 2.0 31 77 9-10-50 .77

52.0 2.6 31 46 10-2-50 .33

50.7 3.1 79 53 10-3-50 .73

44.5 3.0 70 44 10-11-50 .56

53.29 3.15 30.25 55.25 0.30

Table 6

Thermoscreen Errors Observed Between 15:00 and 16:00 O’clock

NAX-1-46 Thermoscreen

Test No. Solar Inten.

Langleys Hour

Wind

MPH

Air Temp.

°F

R. H

$

Date Error

°F

23 6 l „2 3.7 33.3 564' 6-15-52 0.9

27 56.6 2.6 33.7 43 6-16-52 1.1

31 60.7 4.3 36.3 30 6-13-52 1.3

44 61.5 3.9 90.2 34 6-19-52 1.1

Average 60.0 3.75 87.37 4 2 o 0 1.10

Large Wooden Thermoscreen

1A 42.2 2.1 73 53 7-21-50 1.05

2A 55.9 3.6 33 45 7-25-50 .94

3A 50.4 3.1 77 50 7-27-50 1.63

4A 51.0 2.7 35 46 7-29-50 1.25

5A 50.0 2.7 39 51 7-30-50 1.19

6A 26.0 1.3 33 70 3-1-50 1.32

7A 50.7 4.3 73 46 3-4-50 .30

3A 30.9 4.9 79 49 3-6-50 .67

9A 17.9 2.0 77 52 8- 7-50 1.26

10A 52.0 2.5 32 46 3-3-50 1.77

11A 43.9 2.5 35 47 3-30-50 I .65

12A 24.0 2.4 33 62 3-31-50 .94

13A 5.5 1 . 8 , 75 30 9-10-50 1.13

14A 31.5 2.4 30 45 10- 2-50 1.99

15A 27.6 2.5 73 50 10-3-50 1.27

16A 12.0 2.7 69 54 10- 11-50 1.14

Average 35.71 2.75 70.31 53.18 1.23

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