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FM 34-81-1: Battlefield Weather Effects

APPENDIX D

WEATHER EFFECTS ON ARTILLERY

Artillery in the field is heavily weather dependent. Not only must you contend with those weather effects common to all other units but you must also compensate for a number of special effects in the area of target acquisition and aiming. Listed below are weather effects for artillery operations that are not contained in the WTDA tables.

BAROMETRIC PRESSURE. Air pressure affects projectile trajectory, barofuzing, and fire control calculations.

CLOUDS AND SKY COVER. Low ceilings affect target acquisition systems and terminally guided munitions. Low overcast clouds will limit the effectiveness of aerial illumination devices.

DENSITY. The thickness of the atmosphere (heavy air) affects fire control. The greater (heavier) the density, the shorter the range.

HUMIDITY PROFILE. This scale is used to compute virtual temperatures for ballistic firing data.

ILLUMINATION. The best use of most NVD require about a quarter (23 percent) of the moon, 30 degrees above the horizon, scattered clouds, and the sun more than 5 degrees below the horizon. Additional weather products dealing with the use of E-O devices are available from your SWO.

PRESSURE PROFILE. Barometric pressure profiles are essential in both baroarming and barofuzing. They are required for calculating densities for ballistic firing data.

REFRACTIVE INDEX. This index affects radar, laser, and infrared distance measurements.

SURFACE WINDS. Trajectory data and first round hit capability are degraded by high crosswinds. Winds affect the accuracy of rocket fire and Firefinder radar trajectory computations.

SURFACE TEMPERATURE. Frozen ground increases the time a crew has to stabilize their weapon. Extreme cold affects gun accuracy and fuse functioning. High temperature affects stability of ammunition such as white phosphorus (WP). It also reduces rate of fire greatly because of crew heat fatigue.

TEMPERATURE PROFILE. This is another condition that affects calculations of ballistic artillery firing. The profile is used to compute virtual temperatures for artillery firing. Extreme cold affects gun accuracy and fuse functioning.

THUNDERSTORMS AND LIGHTNING. Electrical storms restrict the use of some munitions and fuse types.

VISIBILITY. This affects visual target acquisition, fire adjustment, and E-O target designation. Reduced visibility affects the placement of forward observers (FO) and fire support teams.

WINDS ALOFT. Strong winds aloft impact all ballistic projectile aiming calculations. Accurate and timely meteorological data can compensate for the problem.

WIND PROFILE. Wind profiles play a major role in ballistic wind compensations for artillery firing.