There may be instances when there is no plotting scale available to the NBCC

for the preparation of a wind vector plot. To prepare a wind vector plot in

these instances, the manual method of plotting must be employed.

Though

this method is somewhat more complicated and time consuming the and result

and the principles for plotting are the same as those using the plotting

scale.

When preparing a wind vector plot without the aid of a plotting

scale, there are mathematical adjustments which must be applied to the wind

data. As was pointed out in Part A, the wind direction as received is the

direction from which the wind is blowing.

For wind vector plotting

purposes, this must be changed to the direction toward which the wind is

blowing. To accomplish this, if the given wind direction is more than 3,200

mils, subtract 3,200 mils.

EXAMPLE: Given wind direction is 3900 mils

(direction from which wind is blowing), subtract 3200 mils; result, 0700

mils (direction toward which wind is blowing). If the given wind direction

is less than 3,200 mils, add 3,200 mils. EXAMPLE: Given wind direction is

1500 mils (direction from which wind is blowing) add 3200 mils; result, 4700

mils (direction toward which wind is blowing).

The wind speed given in

knots must be converted to a vector length in kilometers.

This is

accomplished by multiplying the wind speed by the weighting factor from

Table 2-6.

If the wind speed given in the meteorological data for the 6000-8000 meter

layer is 12 knots, you would multiply 12 X .93 (weighting factor from Table

2-6) to find a vector length of 11.2 kilometers.

Once the proper adjustments to the wind data have been completed, the wind

vector plot is drawn using a protractor, a straightedge, and a graphic (bar)

scale (from a map of the scale to which the wind vector plot is to be drawn)

or any other scale convenient to the plotter. The example problem on the

following pages illustrates the procedures to be followed for plotting a

wind vector plot using the manual method.

Assume that the field artillery upper air wind data (Table 2-1 on page 2-4)

have been received by the NBCE. Prepare the fallout wind vector plot.