FM 6-16-3

Field ManualNo. 6-16-3

HeadquartersDepartment of the Army

Washington, DC 15 June 1982

TABLES FOR ARTILLERY METEOROLOGY(ELECTRONIC AND VISUAL)

TYPE 2 MESSAGES

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pittengkDISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited.

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TABLES

TableNumber

Horizontal Distances . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1Feet to Meters Conversion . . . . . . . . . . . . . . . . . . . . . . 2-2Mils to Degrees Conversion . . . . . . . . . . . . . . . . . . . . . 2-3Pressure to Contact Conversion . . . . . . . . . . . . . . . . . 2-4Corrections used to Determine Virtual

Temperature (100%RH) . . . . . . . . . . . . . . . . . . . . . . . 2-5Standard Conditions at Ballistic Zone Midpoints . . 2-6Standard Conditions at Computer Zone Midpoints. 2-7Density Weighting Factors (Type 2 Message)(Surface-to-Air Trajectories). . . . . . . . . . . . . . . . . . . . . 2-8Weighted Densities (Type 2 Message) . . . . . . . . . . . 2-9Wind Weighting Factors (Type 2 Message) . . . . . . . 2-10Weighted Wind Speeds (Type 2 Message) . . . . . . . . 2-11Temperature Weighting Factors (Type 2 Message) 2-12Weighted Temperature (Percent). . . . . . . . . . . . . . . . . 2-13Departure from Mean Surface Density (Percent)

Type 2 Message, Region l. . . . . . . . . . . . . . . . . . . . 2-14

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2-32-662-682-78

2-812-862-86

2-872-882-1052-1062-1182-119

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1-1. Purpose and Scope

a. This manual is a compilation of tablesand charts designed for use in computingtype 2 meteorological messages for theartillery, including ballistic and computermessages. These charts and tables areapplicable for meteorological observationsusing the radiosonde or the pilot balloon. Useof this manual in the computation ofmessages is described in FM 6-15, ArtilleryMeteorology.

b. Users of this manual are encouraged tosubmit recommended changes or commentsto improve the manual. Comments should bekeyed to the specific page, paragraph, andline of the text in which the change isrecommended. Reasons should be providedfor each comment to insure understandingand complete evaluation. Comments shouldbe prepared using DA Form 2028(Recommended Changes to Publications)and forwarded direct to Commandant, USArmy Field Artillery School, ATTN:ATSF-CF-R, Fort Sill, OK 73503.

c. FM 6-16, Tables for ArtilleryMeteorology, has been revised into a set offour field manuals. The set includes—

FM 6-16 Tables for ArtiUery Meteo-rology (Electronic) BallisticType 3 and ComputerMessages.

FM 6-16-1 Tables for Artillery Meteo-rology (Sound Ranging)Messages.

FM 6-16-2 Tables for Artillery Metio-rology (Visual) BallisticType 3 and ComputerMessages and LimitedSurface Observations.

FM 6-16-3 Tables for Artillery Meteo-rology (Electronic andVisual) Type 2 Messages.

1-2. Time Zones, Global Octants, andClimatic Regions

Figure 1-1 divides the world into time zones,global octants, and climatic regions, used inthe heading of meteorological messages.

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SECTION IGENERAL TABLES AND CHARTS

FOR METEOROLOGICAL MESSAGES

2-1. Description of Tables and Charts

The tables and charts in this manual arepresented in sections I, II, and III as follows:

a. Section I, General Tables and Charts forMeteorological Messages. These tables andcharts are used for computing generalmeteorological data from all types ofmeteorological messages.

b. Section II, Tables for Type 2(Electronic), Ballistic Message forSurface-to-Air Trajectories. These tablesinclude the weighting factors and theweighted quantities for density, wind, andtemperature pertaining to the trajectories ofair defense weapons (guns).

c. Section III, Departure Tables for Type 2(Visual), Ballistic Message for Surface-to-Air Trajectories. These departure tables areused in determining ballistic densities for atype 2 message.

2-2. Zone Structure of Atmosphere

For convenience in computing, reporting,and applying corrections, the standardatmosphere is further identified by dividing it

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into zones for standard heights. The zones forthe various meteorological messages areillustrated in figure 2-1.

2-3. Horizontal Distance Tables

a. Horizontal distance tables (table 2-1)are computed for the standard heights of thezone structure as shown in figure 2-l and fora curved earth surface according to thefollowing formula:

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b. In this formula, D is the arc distance ofthe earth’s surface in meters and is theelevation angle to a balloon at standardheight H. R is the average radius of the earth,6,367,650 meters.

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2-4

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2-8

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2-11

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2-12

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2 - 2 2

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2-25

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2-4. Conversion of Wind Speed(Miles per Hour to Knots)

Chart 2-1 is used to convert wind speed in knots and miles per hour.

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2 - 7 2

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2-5. Pressure Conversion (Inches ofMercury to Millibars)

The millibars of pressure for a certain number of inches of mercury may be determined fromchart 2-2.

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2-6. Conversion of Pressure toPercent of Standard

The conversion of surface pressure in millibars to percent of the standard mean sea level(MSL) pressure is accomplished by use of chart 2-3.

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2-7. Pressure to Contact Conversion

The conversion of pressure in millibars to contact value in tenths, or vice versa, isaccomplished by use of table 2-4.

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2-8. Relative Humidity

Relative humidity may be determined by use of a psychrometer and psychrometer tables orby use of chart 2-4.

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2-9. Table of Corrections Used toDetermine Virtual Temperature forPlotting Chart ML-574( )

a. Table 2-5 provides temperature multipliers which, when multiplied by relativehumidity values (i.e., 45% = 0.45, etc.) and added to the observed temperature values, yieldvirtual temperatures.

b. Enter the table with the observed air temperature rounded off to the nearest whole de-gree Celsius and the observed pressure rounded off to the nearest 50 millibars. If theobserved pressure value ends with 25 or 75 (e.g., 925 or 775), round off to the lower50-millibar value. Do not interpolate.

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2-10. Conversion of Surface Densityto Percent of StandardThe surface density, in grams per cubic meter and expressed as a standard surface density,may be determined from chart 2-5.

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SECTION IITABLES FOR TYPE 2, BALLISTIC MESSAGE FOR

SURFACE-TO-AIR TRAJECTORIES

2-11. General

Tables 2-8 through 2-14 contain theweighting factors used in obtaining a type 2message. Some of the tables present theweighting factors directly; in others, theweighting factors are used to determine theeffect of the various zone values on the linevalues of the meteorological message. Theweighting factors used are those agreed to, onan interim basis, by the fifth meeting of theNATO Group on External Ballistics,November 1960.

2-12. Weighted Density Tables(Type 2 Message)

a. The weighted density tables give theweighted densities for the type 2 message(surface-to-air firing) and may be used to

convert zone densities in grams per cubicmeter to zone densities in percent of standardfor that zone, and to convert zone densities tothe weighted effect of these zone densities onthe various line values of the meteorologicalmessage.

b. The values in the density—percentcolumn were computed by dividing theGm/M3 value by the zone midpoint standarddensity.

c. The line-zone number values were com-puted by multiplying the density percentvalues by the weighting factors shown intable 2-8. Line-zone number 21 is the productof the weighting factor (.63), line 2 of zonenumber 1, table 2-8 and the density—percentvalue. Line-zone number 32 is the product ofthe weighting factor (.37), line 3 of zonenumber 2, table 2-8 and the density—percentvalue.

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2-13. Weighted Wind Speed Tables(Type 2 Message)

a. The weighted wind tables maybe used toconvert zone winds to the weighted effect ofthese winds on various line values of themeteorological message.

b. The line-zone number values are theproduct of zone wind values and the weightingfactor values shown in table 2-10. The valuesof line-zone number 21 are the product of zonewind speeds and the weighting factor (.50),line 2 of zone number 1, table 2-10.

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2-14. Weighted Temperature Tables(Type 2 Message)

a. The weighted temperature tables may beused to convert zone temperatures in degreesCelsius to zone temperatures in percent ofstandard for each zone. They may also beused to convert zone temperatures to theweighted effect of temperatures on thevarious line values of the meteorologicalmessage.

b. The zone temperature-percent columnis the quotient of the zone temperature dividedby the standard zone temperature.

c. The line-zone number values are theproduct of the weighting factors shown intable 2-12 and the zone temperature-percentvalues. The line-zone number values of column21 are the product of the weighting factor (.63),line 2 of zone number 1, table 2-12, and thezone temperature—percent values.

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SECTION IIIDEPARTURE TABLES FOR TYPE 2

(VISUAL) BALLISTIC MESSAGE FORSURFACE-TO-AIR TRAJECTORIES

2-15. General

The tables and charts contained in this section are used to determine the departure frommean surface density for the computation of a ballistic meteorological message (visual).

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15 JUNE 1982

By Order of the Secretary of the Army:

E. C. MEYERGeneral, United States Army

Chief of Staff

Official:

ROBERT M. JOYCEBrigadier General, United States Army

The Adjutant General

DISTRIBUTION:

Active Army, ARNG, and USAR: To be distributed in accordance with DA Form 12-11A, Require-ments for Field Artillery Meteorology (Qty rqr block no. 52).

Additional copies may be requisitioned from the US Army Adjutant General Publications Center,2800 Eastern Boulevard, Baltimore, MD 21220.

✰ U.S. GOVERNMENT PRINTING OFFICE: 1982-539-034:137

PIN: 051114-000

FM 6-16-3CoverTABLE OF CONTENTSNOTELIST OF FIGURESLIST OF CHARTSLIST OF TABLESCHAPTER 1. IntroductionPupose and ScopeTime Zones, Global Octants, and Climatic Regions

CHAPTER 2. Meteorological Tables and ChartsSection I. General Tables and Charts for Meteorological MessagesDescription of Tables and ChartsZone Structure of AtmosphereHorizontal Distance TablesConversion of Wind Speed (Miles Per Hour to Knots)Pressure Conversion (Inches of Mercury to Millibars)Conversion of Pressure to Percent of StandardPressure to Contact CoversionRelative HumidityTable of Corrections used to Determine Virtual Temperature for Plotting Chart ML-574( )Conversion of Surface Density to Percent of Standard

Section II. Tables for Type 2 Ballistic Message for Surface-to-Air TrajectoriesGeneralWeighted Density Tables (Type 2 MessageWeighted Wind Speed Tables (Type 2 Messages)Weighted Temperature Tables (Type 2 Messages

Section III. Departure Tables for Type 2 (Visual) Ballistic Message for Surface-to-Air TrajectoriesAUTHORIZATION LETTER