SMITHSONIAN MISCELLANEOUS COLLECTIONS V32

SMITHSONIAN. MISCELLANEOUS COLLECTIONS
VOLUME

114

(WHOLE VOLUME)

SMITHSONIAN
METEOROLOGICAL TABLES
SIXTH REVISED EDITION

Prepared by

ROBERT
Meteorologist, U. S.

J.

LIST

Weather Bureau

SMITHSONIAN INSTITUTION PRESS
CITY OF WASHINGTON


Smithsonian Publication 4014
Sixth revised edition published 1949

Fourth reprint issued 1968

NOV

1

6 2000

n
PREFACE

The

two
and con-

rapid development of .the science of meteorology during the past

made necessary a complete

decades has

revision of both the scope

tents of the Smithsonian Meteorological Tables.

A. Wetmore, Secretary of

the Smithsonian Institution, which has been publishing these tables since
1852, and F.

A

need.

this

sisting of

W.

Weather Bureau, recognized
Weather Bureau meteorologists, con-

Reichelderfer, Chief of the

steering committee of

H. Wexler, Chairman, R. A. Allen,

R. N. Culnan, R. D. Fletcher,

J.

J.

E. Caskey,

Jr.,

P. F. Clapp,

R. Fulks, C. Harmantas, L. P. Harrison,

McGuire, J. Namias, and H. W. Norton, was formed to
make recommendations concerning the new revision and to serve in an
advisory capacity. Funds for the preparation of the manuscript were transferred by the Weather Bureau to the Smithsonian Institution, and under the

W.

C. Jacobs, J. K.

supervision of L. B. Aldrich, Director of the Astrophysical Observatory,

work on

the

new manuscript was

started.

It is a

pleasure to acknowledge

both the administrative cooperation and scientific information received from

Mr. Aldrich.
In preparing this volume, every effort has been made to obtain the latest
and most authoritative data available, and to follow as far as possible the

most recent recommendations of the International Meteorological Organization. Suggestions were also solicited from the various branches of the armed
forces concerned with meteorological problems, from the several universities
having meteorology departments, and from other interested individuals and
organizations. Explanations, sources of data, methods of computation, and
pertinent references accompany all tables. No material on meteorological

codes and symbols, descriptions of meteorological stations, or climatological
data have been included in this revision.
It

would be impossible

to

acknowledge

all

received in the preparation of this volume.

the cooperation and assistance

A

particularly large debt of

owed to L. P. Harrison, Chief of the Technical Investigations
Section of the Weather Bureau, who has unhesitatingly given so much of
his time and attention to this project, and without whose mature judgment
it would have been impossible to complete this work in its present form.

gratitude

is

Grateful acknowledgments are also due to

Towne
all

J.

Scientific School of the University of

A. Goff and

S.

Gratch of the

Pennsylvania for contributing

the material for tables 84-92 and for furnishing the computations for

table 72

;

to S. Fritz of the

the section on radiation

;

to

Weather Bureau for his assistance in preparing
W. D. Lambert and J. A. Duerksen of the Coast

and Geodetic Survey for information concerning gravity and other geodetic


PREFACE

iv

problems

;

to E.

W. Woolard

of the Nautical

Almanac

Office of the

Naval

Observatory for astronomical and related data; and to the many experts
consulted at the National Bureau of Standards. Computations for several of
the longer tables were made by the Machine Tabulation Unit of the Weather
Bureau. Special data or computations for individual tables were furnished
by R. Gunn, I. F. Hand, W. E. Howell, L. D. Kaplan, J. B. Leighly, T. H.
MacDonald, and R. B. Montgomery, all of which have added greatly to the
value of this volume. Permission to reproduce copyrighted material has been

Company, Inc., the McGraw-Hill
and the Reinhold Publishing Cor-

kindly granted by the American Air Filter

Book Company,

Inc., Prentice-Hall, Inc.,

is acknowledged at its point of insertion in the text.
due Mrs. G. B. Morgan for her invaluable assistance in performing many of the computations and in typing the manuscript.
Robert J. List
Washington, D. C.

poration

;

such material

all

Thanks are

also

September

30, 1949.

NOTE TO FIRST REPRINT
Opportunity has been taken in

this

few errors that have been

reprint to correct the

discovered in these tables since the original printing.
Editor.

February 1958

NOTE TO SECOND REPRINT
This reprint corrects three or four errors discovered

in

these tables

since the

first

reprinting.

Editor.

March 1963

NOTE TO THIRD REPRINT
This reprint

is

without change in the text, since no errors have been brought to our

attention since the second reprinting.

Editor.

April 1966


CONTENTS
Page
Preface

iii

Introduction

1

Conversion of units of length and mass

1

Standard gravity for reducing barometric observations

3

Calorie

4
Section

CONVERSION TABLES

I.

Table
9

1.

Conversion factors

2.

Approximate absolute, centigrade, Fahrenheit, and Reaumur tem-

3.

Fahrenheit to centigrade

perature scales

17
.

.

.

20

,,

4.

Centigrade to Fahrenheit

25

5.

Differences Fahrenheit to differences centigrade

6.

Differences centigrade to differences Fahrenheit

29
29

7.

Centigrade degrees per kilometer to Fahrenheit degrees per 1000

8.

Fahrenheit degrees per 1000 feet to centigrade degrees per kilo-

9.

Inches of mercury to millibars

31

10.

Millibars to inches of mercury

38

11.

Millimeters of mercury to millibars

51

12.

Millibars to millimeters of

mercury

59

13.

Inches to millimeters

14.

Millimeters to inches

79

15.

Feet to meters

16.

Meters to feet

92

94

30

feet

meter

30

72

17.

Statute miles to kilometers

18.

Kilometers to statute miles

96
98

19.

Nautical miles to statute miles

100

20.

Statute miles to nautical miles

100

21.

Nautical miles to kilometers

101

22.

Kilometers to nautical miles

101

23.

Days

24.

Time

25.

Hours, minutes, and seconds to decimals of a day
Decimals of a day to hours, minutes, and seconds
Minutes and seconds to decimals of an hour

26.
27.

to decimals of a year

and angle

to arc

102

106

v

106
107

107


smithsonian meteorological tables

vj

Page

Table
28.

29.

Grains to

31.

Grams

32.

Miles per hour

34.

35.

108
109

grams

30.

33.

108

Avoirdupois pounds and ounces to kilograms
Kilograms to avoirdupois pounds and ounces

109

to grains
to knots,

meters per second, feet per second, kilo-

1 10
meters per hour, feet per minute
Meters per second to miles per hour, feet per second, kilometers per
112
hour, knots, feet per minute
Kilometers per hour to knots, miles per hour, meters per second,
113
feet per second

Knots to miles per hour, meters per second,
meters per hour, feet per minute
Section

II.

feet per second, kilo-

115

WIND AND DYNAMICAL TABLES
119

36.

Beaufort wind scale

37.

Geostrophic wind,

38.

Geostrophic wind, constant pressure surface

39.

Geostrophic wind, constant level surface:

constant

pressure

100 geopotential

surface:

120

meter contours
:

200 geopotential foot
122

contours

air density

1

kg. m.~ 3

isobars,

124

,

126

40.

Gradient wind

41.

Coriolis parameter

42.

Inertial

43.

Rossby's long-wave formula

and

130

latitudinal variation

motion

Section
44.

Three millibar

III.

130
131

BAROMETRIC AND HYPSOMETRIC TABLES

Capillary correction for mercurial barometers

45-46.

135

Reduction of the mercury column to standard temperature (explanation)

136

45.

Reduction of the mercury column to standard temperature, English

46.

Reduction of the mercury column to standard temperature, metric

47.

Corrections to reduce barometric readings to standard gravity

48.

Determination of height by the barometer and reduction of pressure

units

139

units

164

to fixed levels

Section IV.

49-51.

203

GEOPOTENTIAL AND AEROLOGICAL TABLES

Relation between geopotential and geometric height
tion)

200

(explana-

217


CONTENTS

Vll

Page

Table
49.

Factors for computing the relation between geopotential and geo-

50.

Geometric meters to geopotential meters

51.

Geopotential meters to geometric meters

52.

Geopotential computations

219

metric height

53-56.

220
222
224

Thickness and mean adjusted virtual temperature of strata be241

tween standard isobaric surfaces (explanation)
53.

Thickness

in geopotential

meters of strata between standard isobaric

surfaces as a function of
54.

Thickness

Mean

56.

Mean

virtual temperature.

.

mean adjusted

virtual temperature.

.

254

adjusted virtual temperature between standard isobaric sur-

255

faces as a function of thickness in geopotential feet

Relation between pressure change and geopotential change (ex-

256

planation)
57.

Change

58.

Change

59.

Change

60.

Change

61.

Change

62.

Change

in height (geopotential meters) corresponding to

change

1

millibar

257

in pressure

in height

change

(geopotential feet) corresponding to

millibar

1

258

in pressure

in height (geopotential feet)

corresponding to a change in

pressure of one-tenth of an inch of mercury

in pressure (millibars)

259

corresponding to a change

in

height

260

of 10 geopotential meters
in pressure (millibars)

corresponding to a change in height

261

of 10 geopotential feet
in pressure (inches of

mercury) corresponding

to a

change

262

in height of 10 geopotential feet

Section V.

STANDARD ATMOSPHERE AND ALTIMETRY TABLES

63.

NACA

64.

ICAN

65.

Altimeter setting computation factors

66.

NACA

67.

Correction of altimeter readings for

265
268
269
273

standard atmosphere, lower atmosphere
standard atmosphere
standard atmosphere altitude-pressure table

mean temperature

of the air

column
68.

NACA

274

standard atmosphere, tentative properties of the upper at-

mosphere
69.

248

adjusted virtual temperature between standard isobaric sur-

faces as a function of thickness in geopotential meters

57-62.

242

of strata between standard isobaric

in geopotential feet

surfaces as a function of
55.

mean adjusted

Density-altitude diagram

280
285


SMITHSONIAN METEOROLOGICAL TABLES

v JiJ

Section VI.

Table
70. Thermodynamic

THERMODYNAMIC TABLES

Density of air

72.

Virtual temperature increment of saturated air

73.

Saturation mixing ratio over water
Saturation mixing ratio over ice

75.

Potential temperature

76.

78.

Two-sevenths power of pressure
Two-sevenths power of ( 1000/p)
Temperature and pressure along saturation pseudoadiabats

79.

Pseudoadiabatic lapse rate

:

80.

Pseudoadiabatic lapse rate

:

81.
82.

Rate of condensation in ascending moist air
Precipitable water in a saturated pseudoadiabatic atmosphere

83.

Lifting condensation level data

77.

84-92.

289
290
295
302
306
308

constants

71.

74.

p

r ™~

314
316
318
323
324
325
327
328

Water stage
Ice stage

Thermodynamic properties

331

of moist air (explanation)

84.

Compressibility factor of moist air

332

85.
86.

Enthalpy residual of moist air

Entropy residual of moist air

87.

Mixing entropy of moist

88.

Isobaric specific heat residual of moist air

334
336
338
339

89.
90.

The
The

91.

Properties of water vapor

341

92.

Properties of condensed water, latent and specific heats

343

coefficient /„

340

coefficient ft

341

Section VII.
93.

air

HYGROMETRIC AND PSYCHROMETRIC TABLES

Definitions and specifications of water vapor in the atmosphere.

94-97.
94.

Saturation vapor pressure over water, metric units

95.

Saturation vapor pressure over water, English units

96.

Saturation vapor pressure over

ice,

metric units

97.

Saturation vapor pressure over

ice,

English units

98-99.
98.

.

.

.

Reduction of psychrometric data (explanation)

Reduction

psychrometric observations

347

350
351
354
360
362

Saturation vapor pressure tables (explanation)

365

368
Reduction of psychrometric observations Fahrenheit temperatures.
369
100. Ratio of the saturation vapor pressure over water to that over ice at
of

99.

:

Centigrade temperatures

.

.

the

same temperature

370

102.

Ratio of the saturation vapor pressure over ice to that over water at
the same temperature
370
Dew point conversion chart
371

103.

Variation of saturation vapor pressure over water with temperature.

101.

372


.

contents

ix

Page

Table

372

104.

Variation of saturation vapor pressure over ice with temperature

105.

Saturation vapor pressure over water of salinity

106.

Equilibrium supersaturation over solution droplets

374

107.

Relative humidity over saturated salt solutions

380

108-109.

Density of pure water vapor

at saturation

.

.

35%

373

(explanation)

381

108.

Density of pure water vapor at saturation over water

382

109.

Density of pure water vapor at saturation over

384

ice

TABLES OF MISCELLANEOUS PHYSICAL PROPERTIES OF
AIR AND AIR-BORNE PARTICLES

Section VIII.

up

389

to about 25 kilometers

110.

Composition of dry

111.

Index

112.

Velocity of sound in air

113.

Viscosity and thermal conductivity of air and diffusivity of water

114.

Terminal velocity of

115.

Size and characteristics of air-borne solids

397

116.

Sizes of atmospheric particles

398

117.

Evaporation of freely falling water drops

398

vapor in

389

390
394

air
fall for distilled

water droplets

in stagnant air.

403

Density of water

Thermal
120. Thermal
121. Thermal
122. Thermal
119.

conductivity of water
conductivity and thermal diffusivity of ice

snow
and density of soils and rocks.

conductivity and thermal diffusivity of
conductivity, specific heat,

123.

Latent heat of melting of sea

124.

Specific heat of sea water

ice

125.

Specific heat of sea ice

126.

Melting point

127.

Depth of water corresponding

in sea

water
to the weight of

snow or

Quantity of rainfall corresponding to given depths
Section X.

129.

407
407

RADIATION AND VISIBILITY TABLES

Blackbody radiation

130-131.

403
404
404
405
405
406
406
406

rain col-

lected in gages of various diameters

128.

396

TABLES OF MISCELLANEOUS PROPERTIES OF WATER
SUBSTANCE AND SOILS

Section IX.

118.

air

of refraction of air

Solar radiation outside the atmosphere (explanation)

411

414

130.

Intensity of solar radiation outside the atmosphere

415

131.

Energy

416

distribution of solar radiation outside the atmosphere


.

smithsonian meteorological tables

x

Page

Table
132-134.

Total solar radiation at the top of the atmosphere (explana-

417

tion)

132.
133.

Total daily solar radiation at

418

the top of the atmosphere

Total annual and seasonal solar radiation

at the top of the at-

418

mosphere

134. Chart of the total daily solar radiation at the top of the atmosphere. 419
135-136. Total direct solar radiation reaching the ground with various
420
atmospheric transmission coefficients (explanation)
135.

Total daily direct solar radiation reaching the ground with various

136.

Total annual and seasonal direct solar radiation reaching the ground

137.

Optical air mass corresponding to different zenith distances of the

138.

Absorption of radiation by water vapor, 10-25/x

139.

Absorption of radiation by water vapor,

140.

Transmission of solar radiation by water vapor,

141.
142.

Absorption of radiation by carbon dioxide
Absorption of radiation by ozone

143.

Absorption coefficients of oxygen

144.

Transmission of radiation through pure, dry

145.

Scattering of solar radiation by water vapor

146.

Transmission of solar radiation by the atmosphere, 5.5-22/*
Transmission of solar radiation through moist air

421

atmospheric transmission coefficients

422

with various atmospheric transmission coefficients

422

sun

147.

423
425

1.3-9/u.

425
427

0. 7-2.2/*

428
430
431

air

432
433
436
438

148.

Spectral distribution of solar radiation at sea level

149.

Total solar and sky radiation on a horizontal surface during cloud-

150.

Relation between the vertical component of direct solar radiation

151.

Relation between average sunshine and solar radiation on a hori-

152.

154.

Transmission of solar radiation through clouds (overcast)
Relation between illumination and total radiation
Albedo of various surfaces

155.

Reflectivity of a water surface

156.

Absorption of radiation by pure liquid water
Absorption of radiation by sea water

438

less conditions

and

total solar

and sky radiation on a horizontal surface

439

zontal surface

153.

157.

440

158.

Scattering area coefficients for water drops in air

159.

Relative spectral luminosity for the
levels

160.

Horizontal

•.

visibility

human

441

442
442

:

444
445
446
446

eye at various luminance

448
452


CONTENTS
rr

Table

Section

XI

XL GEODETIC AND ASTRONOMICAL TABLES

-,-,

Page

Geodetic and astronomical constants

481

Length of one degree of the meridian
163. Length of one degree of the parallel
164. Distribution of water and land in various

482
483
484
485
486
488
491
493
495
497

161.

162.

map

latitude belts

165.

Scale variation for standard

166.

Radius of curvature on a polar stereographic projection

167-168.

projections

Acceleration of gravity (explanation)

167.

Acceleration of gravity at sea level

168.

Relative acceleration of gravity at sea level

Ephemeris of the sun
170. Solar altitude and azimuth
171-174. Duration of daylight, civil
169.

twilight,

and astronomical twilight

(explanation)
171.

506
507

Duration of daylight

172.

Duration of

173.

Duration of astronomical twilight
Daylight and twilight for southern latitudes
Index

174.

civil twilight

513

U>&

lwA-"

517
520
521



'

:

INTRODUCTION
CONVERSION OF UNITS OF LENGTH AND MASS
United States usage.

— No

to be used in the conversion

general agreement yet exists on the factors

between the metric and the English systems of

In the United States, an Act of Congress of July 28, 1866 (14 Stat.
339; 15 U.S.C. 204) established the metric system as lawful throughout the
United States and ordered the units of weights and measures in common
use to be defined in terms of this system. A schedule annexed to this Act
units.

established 39.3700 inches as the equivalent of the meter

and 2.2046 pounds

(avoirdupois) as the equivalent of the kilogram. In 1893 T. C. Mendenhall,

Superintendent of Standard Weights and Measures, issued an order

*

stating

would regard the International Prototype Meter and Kilogram 2
as the fundamental standards and affirmed the equivalents of the Act of 1866.
In actual practice, the National Bureau of Standards still uses the length
that his office

ratio

annexed to

this Act,

which yields

1

=

inch

2.540005 centimeters.

How-

Bureau of Standards has adopted
the results of a comparison of the British Imperial Standard Pound and the
International Prototype Kilogram made in 1883, 1 pound = 453.5924277
grams, rather than the ratio annexed to the Act of 1866, which yields 1
pound = 453.597+ grams.
ever, in the case of the pound, the National

British usage.

mass are

—In

Great Britain, the English standards of length and

by the Imperial Standard Yard and the Imperial

legally defined

Standard Pound, respectively, and the relation of the English to the metric
units are experimentally determined

now

legally sanctioned in

1

1

Recent comparisons.
1

inch

pound

=
=

3
direct comparison.

The conversions

2.539998 centimeters

453.59234 grams

—According

Imperial
1

by

Great Britain are:

Yard

meter
1

inch

_
~
=

to the

most recent comparisons

3600000
3937014

>

4

which yields

2.539996 centimeters

U. S. Coast and Geodetic Survey, Bull. 26, 1893.
Prepared by the International Bureau of Weights and Measures, Sevres, France.
This bureau was established by the International Metric Convention, 1875, and is supported by the contributions of many nations, including the United States.
8

For a discussion of the problems involved, see Darwin, C, et al., Proc. Roy. Soc.
London, ser. A, vol. 186, p. 175, 1946.
4 Nat. Bur. Stand., private communication,
July 1949.
1

2

1


;

SMITHSONIAN METEOROLOGICAL TABLES

2

in the conversion:
In the case of the pound, this comparison resulted
1

pound

=

453.59234 grams

have
Industrial usage.— In recent years improved industrial techniques
Englishvarious

the
by
used
relationships
made it desirable to standardize the

The conversion

speaking countries.

1

inch

=

2.54 centimeters has been sug-

gested as the best compromise, with the practical advantage of

facilitating

mechanical conversion between the two systems by means, for example, of a
127-tooth gear wheel on a lathe or measuring instrument. The above relation-

American and British industrial use for several
5
years and has been adopted by both the American Standards Association
6
and the British Standards Institution.

Even less practical difference exists between the various definitions of the
pound, but the conversion 1 pound = 453.5923 grams has been urged, since
ship has been the standard for

this figure is divisible

At

this writing a

by 7000, the number of grains

bill

to legalize these

pound.

in a

two conversions has been prepared

for introduction in Congress and the British are expected to legally sanction

them by an Order

in Council

has already adopted the

Accordingly,
in this

upon enactment of the

new conversion

bill

into law.

Australia

factors.

conversions between the English and metric systems

all

volume are based on the relationships:
1
1

Nautical mile.

inch

=

2.54 centimeters

pound = 453.5923 grams

— Originally

and

practically for uses at sea, the nautical

mile was considered to be the length of

1

minute of arc on the earth's surface

for the given latitude and in the given azimuth on a representative spheroid.

more

precise definition

is

desirable

and

in the tables issued

by the U.

of Standard Weights and Measures, September 1898, the nautical mile
defined as a minute of arc of a great circle on a sphere
that of the Clarke spheroid of 1866.

mile by the

National Bureau of

The

value

Standards

7

now
is

Clarke's ratio of the foot to the meter this length

6080.20

is

feet,

8

given for the nautical

6080.27

feet, the

Using
value

8

given in Bowditch

adoption of the

is

whose surface equals

1853.248 meters.
is

A

S. Office

using the ratio annexed to the Act of 1866 this length
the value given in previous editions of these tables. The

new

ratio of the foot to the

American Standards Association Report B

meter (1 foot

48.1,

=

0.3048 meter)

"Inch-Millimeter Conversion

for

Industrial Use," 1933.
6

British Standards Institution Report B. S. 350, "Conversion
Factors

7

U.

8

Navy Hydrographic

and Tables,"

1944.

M

Nat. Bur. Stand. Misc. Publ.
121, 1936.
Bowditch, N., American Practical Navigator, 1938 rev.
S.

Office,

Washington, 1939.

On

ed., pp. 20 and 327.
U. S.
page 144 the factor 6080.20 is given.


INTRODUCTION
results in the following definition of the

U.

6

S. nautical mile,

which

used

is

throughout this volume:

U.

1

S. nautical

mile

=

1853.248 meters

=

6080.21 feet

Other definitions of the nautical mile are in use. The British Admiralty
6080 feet (exactly) the international

defines the nautical mile as being

nautical mile

;

defined as being 1852 meters (exactly). 1111

is

STANDARD GRAVITY FOR REDUCING BAROMETRIC OBSERVATIONS
common

Prior to the introduction of the millibar as the

unit of pressure in

was customary to express barometric pressures in terms of
the height of a column of mercury reduced to standard conditions of tempera-

meteorology,

it

ture and gravity.

gravity adopted

To

Conventionally, the standard value for the acceleration of

was

that at latitude 45°

and sea

level.

9

reduce units of pressure expressed in terms of the height of a mercury

column to standard gravity,

it is

only necessary to

know

the ratio of the local

In general, this ratio

acceleration of gravity to the standard value.

de-

is

terminable with more precision than the absolute value of the acceleration of
gravity at a given place.

However,

absolute units (e.g., millibars),

if

pressures are to be converted to

necessary to

it is

know

the standard acceleration

of gravity.

At

meetings of the International Committee on Weights and

the 1891

made

in

10

announced the results of an investigation
1888 which yielded an acceleration of gravity at latitude 45° and

Measures, Defforges and Lubanski

sea level of 980.665 cm. sec." 2 This value has been used extensively since that

time by physicists and others as an arbitrary standard value of gravity,

though

it

has long been

known

that

it

gravity at latitude 45° and sea level. 11
that the best value

is

The most

near 980.616 cm.

Most meteorological

al-

does not represent the absolute value of

sec."

2

recent determinations indicate

(see Table 167).

services, including the

U.

S.

Weather Bureau,

first

reduce barometer readings in terms of inches or millimeters of mercury to
gravity at latitude 45° and sea level (g 45 o) by means of a correction depending
,

on the

ratio of local gravity to

lute units.

Strictly speaking,

g i5

it is

,

(see Table 47) and then convert to abso-

therefore necessary to use the best estimate

of the value of gravity at latitude 45°

and sea

level in converting the inch or

millimeter of mercury to millibars. This procedure

was adopted by the

national Meteorological Organization in 1939 (Resolution 25, Berlin).

ever, for

many

Inter-

How-

physical applications (e.g., the definition of the International

Temperature Scale, 1948, see footnote, page 17) one atmosphere is defined as
1013.250 mb. This pressure corresponds to the pressure exerted by a column
International Meteorological Tables, Paris, 1890.
10

Defforges and Lubanski, Com. Int. des Poids

11

Dryden, H.

lla Effective

L.,

July

et

Mes., Ann.

Nat. Bur. Stand. Journ. Res., vol. 29,
1,

1954,

I, p.

135, Paris, 1892.

p. 303, 1942.

the international nautical mile

Department of Defense and the Department of Commerce.

was adopted bv the L.

S.


SMITHSONIAN METEOROLOGICAL TABLES

4
of

3
to
mercury 760 mm. high, having a density of 13.5951 gm. cm.' and subject
2

a gravitational attraction of 980.665 cm. sec."
millimeter
distinction is therefore necessary between the standard inch or
-2
"45°"
of
millimeter
or
inch
and the
of mercury based on 980.665 cm. sec.

A

mercury based on 980.616 cm. sec." (see Table 1). Owing to the action of
adopting the conthe International Committee on Weights and Measures, in
2
ventional standard value 980.665 cm. sec.," it is advisable to employ this datum
2

for

Accordingly, with a view to maintaining conon which the International Temperature Scale of 1948

barometric readings.

all

sistency with the basis

established, the tables presented herein for conversions of inches or millimeters of mercury to millibars, and vice versa, are based on the conventional
2
standard acceleration of gravity (980.665 cm. sec." ).

is

If

it is

desired to convert "45°" inches or millimeters of mercury to milli1 1 must be decreased by 0.005 percent.

bars, the tabular values in Tables 9 and

Conversely,

if

millibars are to be converted to

of mercury, the tabular values in Tables 10

"45°" inches or millimeters

and 12 must be increased by

0.005 percent.

CALORIE

15° gram-calorie.

—The small- or gram-calorie

12

was

originally defined as

the quantity of heat necessary to raise the temperature of
1

degree centigrade.

It

temperature over which the water was heated and

many such

calories,

it

depending on the range. The

to 15.5°

gram of water

became possible

C, has

until recently

to define

15° gram-calorie (cal.i 5 ),

the quantity of heat necessary to raise the temperature of

from 14.5° C.

1

was found necessary to specify the exact range of

1

gram

been one of the most

of water

common

units of heat used in scientific work.

International

Steam Tables

calorie.

—Modern laboratory procedures for

the determination of amounts of heat usually involve electrical apparatus and
it

has been found advantageous to define the calorie in terms of electrical

equivalents.

Tables

18

Therefore

in

1929 the First International Conference on Steam

defined the International

equivalent to 1/860

xlO 3 mean

international kilowatt-hour

=

nition has also been adopted

Steam Tables

calorie

(ITcal.) as being

international kilowatt-hours,

where

1

mean

1.00019 absolute kilowatt-hours. 14

This defiby the International Meteorological Organiza-

12

The

13

Mech. Eng.,

14

In the United States, the National Bureau of Standards uses the relation 1 inter1.000170 absolute joules, where the "international joule" is the inter-

large- or kilogram-calorie

national joule

(Kcal.) has not been used in this volume.

vol. 52, p. 120, 1930.

=

national joule as maintained in this country, and not the

mean

international joule.

definition yields the relation:
1

ITcal.

=

4.18674 absolute joules

=

4.18605 international joules.

This


:

INTRODUCTION
tion.

15

The

gram-calorie

relation of the International
is

5

Steam Tables

15°

calorie to the

16
1

ITcal.

Meteorological practice.

=

1.00032

cal. 15

— From the relationship above,

it is

evident that

for most ordinary meteorological purposes the difference between the
calorie

and the 15°

calorie

is

negligible.

However,

it is still

the 15° calorie in radiation and associated fields of meteorology, while the
calorie has

become the standard for use

in

thermodynamic

calculations.

dual usage has been adopted in general throughout this volume.
instances the type of calorie

such that the difference
15 Int.

is

is

unspecified

;

IT

This

In some

here the nature of the data

is

immaterial.

Meteorol. Org. Twelfth Conference of Directors, Resolution 164, Washington,

1947.
16

IT

customary to use

See Birge, R.

T.,

Rev. Mod. Phys.,

vol.

13, p. 233,

1941.

(#b\

JL



Section

I

CONVERSION TABLES
~1

%h\



Table

1

CONVERSION FACTORS

1

Organization of Table

A. Length

K. Energy, work

Mass

F.

D. Time

I.

Pressure

L. Power
M. Energy per unit area
N. Power per unit area

E. Velocity; speed

J.

Force

O. Illumination, brightness,

G. Density, specific volume

Area
Volume

B.
C.

H. Viscosity

etc.

A. Length:
1

Angstrom unit (A.)
= 10"V

1

= 25.4 mm.
= 2.54 cm.

= 10-»cm.
=

1

micron

10- 10

=
=

m.
1

(ft)

= 10

in.

A.
KT* cm.
1
= 10" cm.
= 10^ m.
= 0.039370079
1

1-

ft.

in.

centimeter (cm.)

1

= lO" m.

= 0.39370079
= 0.032808399

ft.

in.
1

ft.

ft.

1

ft.

statute mile

(stat.

mi.)

= 5280
= 0.868391 naut. mi.
= 1609.344 m.
= 1.609344 km.
ft.

in.

kilometer (km.)

= 10 cm.
= l(fm.
= 3280.8399
= 0.621371
mi.
= 0.539593 naut. mi.
B

1

ft.

ft.

stat.

degree of latitude* (°lat.)

= 111137 m.
= 111.137 km.
= 69.057
mi.
= 59.969 ss 60 naut.

U. S. nautical mile (naut. mi.) t

= 6080.21
= 1.151555

= 1853.248 m.
= 1.853248 km.

stat.

1

rod (rd.)

= 16.5
= 5.0292 m.

meter (m.)
10* cm.

=
= 3.2808399
= 39.370079

1

fathom (fath.)

=6
= 1.8288 m.

8

1

yard (yd.)
36 in.

=
=3
= 91.44 cm.
= 0.9144 m.

(mm.)

millimeter

foot (ft.)

= 12
= 30.48 cm.
= 0.3048 m.

4

1
1

inch (in.)

1

British Admiralty nautical mile

1

International nautical mile

= 6080

stat.

mi.

mi.

ft.

= 1852 m.
= 6076.1
= 1.150779

ft.

stat.

mi.

B. Area:
1

square millimeter (mm.*)

= 0.001550003
*

1

square inch

Average value, 1/90 of meridian quadrant.

t

See Introduction,

1

1 in.
1 lb.

=
=

2.54 cm.
453.5923

in bold-face type.

(continued)

g.

3

p. 2.

See Introduction for discussion of the basic conversion factors adopted.
conversions are based on the factors:

SMITHSONIAN METEOROLOGICAL TABLES

(in. )

= 6.4516 cm.

8

in.

Fundamental conversion factors are

2

All

metric-English unit


Table

10

1

(continued)

CONVERSION FACTORS
B. Area: (continued)
1

square centimeter (cm.')

= 10' ram.
= 0.1550003

1

square foot

1

s

in.'

8

4

1

in.'

square meter (m.')

= 10 cm.
= 1550.003
= 1076391

(ft.')

= 144
= 929.0304 cm.
= 0.09290304 m.'

1

1

)

=9
= 8361.2736 cm.'
= 0.83612736 m.'
ft.'

in.'
8
ft.

(km.')

square kilometer

2

square yard (yd.

= 10 cm.'
= 10" m.'
= 1.076391 X 10
= 247.1054 acre
= 0.3861022
10

1

acre

= 43560
= 4840 yd.'
= 4046.8564 m.'
ft.'

7

ft.'

stat. mi.'

1

square statute mile

(stat. mi.

= 2.78784 X 10
= 640 acres
= 2.58999 km.

2

)

7

ft.'

3

C.

Volume:
1

cubic centimeter

(cm.

= 0.999972 ml.
= 0.0610237
= 0.0338140 U.

8

1

)

cubic inch (in.

in.*

1

cubic meter (m.

= cm.
= 999.972
= 35.3147
= 264.172
10"

= 219.97
1

milliliter

8

)

S.

fl.

oz.

or stere (s.)

1

8

ft.

Brit. gal.
1 fluid

its

8

fl.
fl.

oz.

oz.

fl.

oz.)

fl.

oz.)

8

in.

density.)
8

1

8

U.

quart, liquid,

in.

fl.

S.

oz.

fl.

(U. S.

S.

= 57.75
= 32 U. S.
= 946.353 cm.
= 0.946326

8

8

fl.

oz.

8

1.

fl.

1

gallon,

U.

S.

(U. S. gab)

= 231 in.3
= 128 U. S.
= 133.23 Brit.
= 0.83267 Brit.
= 3785.41 cm.
= 3.78531

fl.

8

1.

(continued)

SMITHSONIAN METEOROLOGICAL TABLES

oz.

8

maximum

= 1000.028 cm.
= 61.0255
= 33.815 U. S. oz.
= 1.05672 U. S. qt.
= 0.264179 U. S. gal.

= 35.196 Brit. oz.

fl.

fluid ounce, British (Brit.

= 1.7339
= 28.413 cm.
= 28.412 ml.
= 0.96076 U.

volume

kilogram of water

in.

gal.

8

8

temperature of

qt.

ounce, U. S. (U. S.

= 1.80469

= 29.5735 cm.
= 29.5727 ml.
= 1.0408 Brit.
1

1

8

in.

(1 liter is defined as the

at

oz.

1.

(ml.)

(1.)

occupied by

fl.

8

S. gal.

8

liter

S.
8

(ft. )
in.

in.

)

= 1728
= 29.9221 U. S.
= 7.48052 U. S.
= 28316.8 cm.
= 28.3161

1.

= 1.000028 cm.
= 0.0610255
= 0.033815 U. S.
= 0.035196 Brit.
1

cubic foot

8

U.

8

= 0.554113 U.
= 16.3871 cm.
= 16.3866 ml.

oz.
fl.

oz.

gal.

qt.)


Table

(continued)

1

11

CONVERSION FACTORS

C. Volume: (continued)
1

gallon, British (Brit, gal.)

(Im-

perial gallon)
(1

British gallon

defined as

is

the volume occupied by 10 pounds
of water at 62° F.)

= 160 Brit. oz.
= 277.42
= 1.2010 U. S. gal.
= 153.72 U. S. oz.
= 4546.1 cm.
= 4.5460
fl.

in.»

fl.

3

1.

D. Time:
1

mean

solar second (sec, s.)

= 1.002738
1

mean

1

mean

sidereal seconds

solar minute (min., m.)

= 60

(mean

sec.

solar)

solar hour (hr., h.)

= 3600 sec. (mean solar)
= 60 min. (mean solar)
1

mean

solar day (da., d.)

= 86400 sec. (mean solar)
= 1440 min. (mean solar)
= 24 hr. (mean solar)
= 24 hours 3 minutes 56.555
1

tropical

(mean

solar,

seconds of

mean

sidereal time

ordinary) year (yr.)

= 31.5569 X 10* sec. (mean solar)
= 525949 min. (mean solar)
= 8765.81 hr. (mean solar)
= 365.2422 da. (mean solar)
= 366.2422 sidereal days
1

sidereal second

1

sidereal

= 0.997270 sec.

(mean

solar)

day

= 86164.1
= 23 hr.

(mean

sec.

solar)

56 min. 4.091 sec. (mean solar)

Velocity; speed:
1

meter per second (m.

sec."

= 3.6 km. hr."
= 1.94254 knots
= 2.23694 mi. hr."
= 3.28084 sec."
= 196.850 min."
= 0.77742
day

1
,

mps)

1

-1

1

1

1

1

ft.

1

1

ft.

°lat.

1

1

1

ft.

kilometer per hour

1

1

(km.

ft.

hr.

-1

°lat.

,

kph)

= 0.277778
= 0.539593
= 0.621371
= 0.911344
= 0.21595

1

m.

sec."

-1
,

1

ft.

-1

1

mi. hr."

sec.

1

°lat.

mile per hour (mi. hr.

= 0.868391 knot
= 1.46667 sec."
= 0.44704 m.
= 1.609344 km. hr.= 88 min."
= 0.34754 Mat. day"

1

knot

ft.

knot

= naut. mi. hr.
= 1.15155 mi. hr."
= 1.68895 sec."
= 0.514791 m. sec."
= 1.85325 km. hr."
= 101.337 min."
= 0.40021 s* 0.4

1

sec."

day"

1

1

1

ft.

1

(continued)

SMITHSONIAN METEOROLOGICAL TABLES

day"

mph)


Table

12

1

(continued)

CONVERSION FACTORS
E. Velocity; speed: (continued)
1

degree of latitude per day (°lat.

1

foot per second

)

= 1.2863 m. sec."
= 4.6307 km. hr."
= 2.4987 =* 2.5 knots
= 2.8774 mi. hr.
1

1

1

1

ft.

1

1

1

foot per minute

min.

(ft.

-1
,

= 0.00986808 knot
= 0.0113636 mi. hr."
= 0.00508 m. sec."
= 0.018288 km. hr."
1

1

F. Mass:
1

gram

1

(g.)

grain (gr.)

= 0.0647989 g.
= 0.00228571 oz.

= 15.4324 gr.
= 0.0352740 oz.
= 0.002204623

lb.

1

1

ounce avoirdupois (oz.)

= 437.5 gr.
= 28.3495 g.

kilogram (kg.)

= 10
= 35.2740 oz.
= 2.204623
s

g.

1

pound avoirdupois

= 7000 gr.
= 16 oz.
= 453.5923
= 0.4535923

lb.

1

metric ton, tonne

(t.)

= 10 kg.
= 2204.623
= 1.10231 short tons

= 0.9842107 long ton
s

(lb.)

g.

lb.

1

kg.

short ton

= 2000
= 0.892857 long
= 907.1846 kg.
= 0.9071846
lb.

ton

t.

1

long ton

= 2240

= 1.12 short tons
= 1016.047 kg.
= 1.016047
lb.

t.

G. Density,
1

specific

volume:
3

g. cm."*

1

= 62.4280
=
m."*

lb. ft."

= 0.0160185

3
lb. ft."

1

1

cm. 8

t.

1

3

ft.

lb."

g.

ft.

3

3
S

1

lb."

H. Viscosity

1

poise

= g. cm."
= 0.002089
1

1
1

sec."
lb.

(wt.)

sec.

3

ft."

(continued)

SMITHSONIAN METEOROLOGICAL TABLES

lb.

(wt.) sec.

= 478.8

1

cm.

1

= 62.4280 cm.

g." 1

= 0.0160185

\ fps)

sec.

(ft.

= 0.592085 knot
= 0.681818 mi. hr."
= 60 min."
= 0.3048 m. sec."
= 1.09728 km. hr."

1

day"

3

ft."

poises

„
g

-1

1

fpm)


Table

1

(continued)

13

CONVERSION FACTORS
I.

Pressure:

N ot e. — The

pressure units one standard inch of mercury, one standard millimeter
and one standard atmosphere are denned in terms of the conventional
2
standard value of gravity 980.665 cm. sec." which was adopted by the InternaThese units have been proposed for
Measures.
tional Committee on Weights and
general meteorological use. The pressure units one 45° inch of mercury, one 45°
millimeter of mercury, and one 45° atmosphere are defined in terms of the best
2
value of gravity at 45° latitude and sea level, 980.616 cm. sec." See introduction,
of mercury,

,

page

3.

centimeter

dyne per square
1
(dyne cm." )
1 barye
10"8 mb.
10^ bar.

1

1

standard inch of mercury

= 0.491154
= 33.8639 mb.
= 0.0345316 kg. cm."
= 25.4013 mm. Hg. (45°)

=
=
=

lb. in."

= 10 dynes cm."
= 0.00101972 kg. cm."
= 0.750099 mm. Hg. (45°)
= 0.750062 mm. Hg. (stand-

= 25.4 mm. Hg.

3

3

2

1

45°

in.
in.

= 0.0145038

lb.

lb.

in."

2

6

1

dynes cm.

s

mb.

a

barye

,

in.
in.

Hg. (45°)
Hg. (stand-

ard)

= 1.333224 mb.
= 0.001359504 kg. cm."
= 0.03937205 Hg. (45°)
= 0.03937008 Hg.( stand2

in.

in.

ard)
2

lb.

2

ard)
1

standard atmosphere

= 1013.250 mb.
= 1.03323 kg. cm."
= 760 mm. Hg. (standard)
Hg. (stand= 29.9213
2

in.

in."

(mm.

45° millimeter of mercury

ard)

= 14.6960
= 760.038 mm. Hg. (45°)
= 29.9228
Hg. (45°)
= 1.000050 45° atmosphere
lb.

Hg. (45°))

= 0.999950 mm.

Hg.( stand-

in.

ard)

= 1.333157 mb.
= 0.00135944 kg. cm."
= 0.03937008 Hg. (45°)
= 0.0393681 Hg. (stand2

in.

in.

ard)

= 0.0193358

2

(lb. in."

= 68.9476 mb.
= 0.0703069 kg. cm."
= 51.7175 mm. Hg. (45°)
= 51.7149 mm. Hg. (stand-

(mm. Hg. (standard))
= 1.000050 mm. Hg. (45°)

1

pound per square inch

= 2.03612
= 2.03602

-2

standard millimeter of mercury

= 0.0193368

2

psi)

bar (b.)

= 10
= 10
= 10

in."

ard)
1

= 10 mb.
1

Hg.

2

Hg. (45°)
Hg. (stand-

(cb.)

centibar

(in.

= 0.491130
= 33.8622 mb.
= 0.0345298 kg. cm."
= 25.4 mm. Hg. (45°)
= 25.3987 mm. Hg. (stand-

ard)

1

(standard)

inch of mercury

(45°))

ard)

= 0.0295315
= 0.0295300

2

2

millibar (mb.)

1

(in.

Hg. (standard))

lb. in."

2

{continued)

SMITHSONIAN METEOROLOGICAL TABLES

in."

2