PART C - PREPARE A WIND VECTOR PLOT USING THE MANUAL METHOD
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.
1.
Example.
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.
2.
Situation.
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.
NOTE:
To convert mils to degrees divide the number of mils
by 17.8.
2-17
CM5206
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