Column 13 is headed “Change of range for wind component in plane of fire of 10 knots,” and column 16 is headed “Deviation for lateral wind component of 10 knots.”
A wind, or wind component, in the plane of fire, or line of fire, is spoken of as a range wind. A lateral wind (wind, or wind component, blowing across the line of fire) is spoken of as a cross wind.
The effect of a positive range wind (blowing in the direction in which the projectile is traveling) is to increase the range. The opposite is true for a negative range wind. A cross wind will carry the projectile in the direction toward which the wind is blowing. The method of deriving the values in these columns is quite involved, and will not be treated in this text.
The use of the columns is similar to that described in article 17B8, and will not be repeated. The direction of the errors having been found, care must be taken to apply the corrections in the proper direction. The error is in the direction toward which the wind is blowing; hence the correction must be in the opposite direction.