4.
Plotting Field Artillery Upper Air Wind Data.
The following procedures are followed in the preparation of a wind vector
plot, using the plotting scale and U.S. Army Field Artillery upper air wind
data.
Step 1.
Attach overlay paper to a piece of graph paper, a map, a firing
chart, or any other paper with parallel lines that can serve as
north-south grid lines.
Mark GZ, scale, and grid north on the
overlay paper.
Step 2.
Lay the plotting scale on the chart so that the hole at the end
of the slot labeled "0-2" lies over the starting point (GZ).
Step 3.
Secure the scale to the chart by inserting a sharpened instrument
(hard lead pencil or a pin) through the hole, and rotate the
scale so that the line on the azimuth dial representing the wind
direction for the lowest (0 to 2,000 meters) wind layer is
parallel to the north-south grid lines and is oriented with the
azimuth representing the wind direction pointing north.
Note
that the wind direction in this case is the wind direction as
read directly from the field artillery upper air wind data.
Step 4.
Hold the scale firmly and, using the "0-2" slot, draw a line to
the point which represents the wind speed in knots for the 0 to
2,000 meter layer as read directly from the field artillery upper
air wind data.
This point will be determined by using the map
scale selected (indicated by the color legend from the plotting
scale). Lift the scale and mark this point with the number 2 (to
indicate the top of the layer it represents).
Draw a small
circle "O" at the end of the vector just drawn (Figure 2-2 on
page 2-13).
Step 5.
Next move the scale so that the hole at the end of the slot
labeled "2-4" lies over the outer end of the wind vector just
plotted.
Orient the scale in the manner described in Step 3;
however, this time use the wind direction for the 2,000 to 4,000
meter layer.
Using the "2-4" slot, draw a line to the point
representing the wind speed in the 2,000 to 4,000 meter layer.
Lift the scale and mark this point with the number 4, and add a
small circle (Figure 2-3 on page 2-14).
2-11
CM5206
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