Wind Vector Plots  

Mean wind information is used to construct vector plots, which are used to determine the zones of the most hazardous radioactive fallout, Wind direction is converted into downwind directions, and wind speed is converted into vector lengths.

To plot wind vectors, first add 180 degrees to or subtract it from the wind direction given for each layer. This gives you vector direction. Vector direction of 090.

Next, determine vector length. Convert mean wind speed for each layer into vector length, using tables 6-9-1 (A or B), 6-9-2 (A or B), or 6-9-3 (A or B). Each table is based on a map scale (1:50,000, 1:100,000, or 1:250,000) and a unit of measurement for wind speed (kilometers per hour or knots). REMEMBER: IF THE RADFO MESSAGE BEGINS WITH NAV, YOU MUST USE THE VECTOR LENGTH TABLES RE-FERRING TO KNOTS. Vector length is in centimeters. For example, if the mean speed in a layer is 20 knots and you are working with a map with a scale of 1:100,000, vector length will be 25.2 centimeters.

The next step is to plot the wind vectors. First, label ground zero GZ and grid north GN. GZ is the location of the blast. Second, from GZ, draw the vector for the first layer (surface to 2,000 meters) and label the end of the vector with a 2. From the end of the first-layer vector, draw the second-layer vector (2,000-to-4,000-meter layer) and label the end point with a 4. Plot all of the remaining vectors in the same manner. The final result of plotting wind vectors will be a single vector plot, as shown in figure 6-9-2.

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