AEROGRAPHER'S MATE 3 & 2 



The following procedures are employed for 

 plotting most codes, and have generally been 

 standardized so that the minimum amount of 

 confusion will result: 



1. Indicator figures for code groups are not 

 plotted. 



2. Most wind directions are reported in tens 

 of degrees. The wind direction, dd, is plotted 

 as the wind direction, in tens of degrees, from 

 which the wind is blowing. When the direction 

 is missing, the ddff portion of the message is 

 not normally plotted. 



3. All wind speeds are plotted in knots. 

 They are plotted as shown in the winds aloft 

 section of chapter 17, 



a. A half barb (1/8 inch) represents 5 

 knots. 



b. A full barb (1/4 inch) represents 10 

 knots. 



c. Pennants (1/4 inch) represent 50 knots. 



d. A calm wind consists of a circle drawn 

 around the station circle. 



Any combination of a, b, and c may be em- 

 ployed to represent the correct speed. You 

 should plot "X" at the end of the wind shaft 

 when the speed is missing. 



4. Wind direction and speed are usually plot- 

 ted first so that true direction may be shown, 

 and interference with other elements plotted 

 is kept to a minimum. 



5. Minus signs are plotted with subzero tem- 

 peratures. 



6. If any mandatory plotted element is gar- 

 bled or partly or wholly missing, plot the letter 

 "M" in its place. 



7. All elements that are plotted are oriented 

 to the adjacent latitude and longitude lines. 



8. All legends should be filled out as indi- 

 cated in the printed portion of the map contain- 

 ing the legend block, if a legend block is missing, 

 information normally entered in the printed legend 

 is entered in the lower left-hand corner of 

 the map. The entries may be rubber stamped 

 or printed block entries. Do not forget your 

 name and rate in the legend. 



9. Data plotted around a station circle should 

 cover an area not greater than a dime if pos- 

 sible. 



10. The code figures that are coded for tem- 

 perature (TT) and dewpoint (TdTd) are reported 

 and plotted as whole degrees Celsius. 



11. When plotting of the *nap has been com- 

 pleted, check the following items: 



a. Neatness 



b. Wind direction and speed plotted cor- 

 rectly. 



c. Size of station plots. 



d. Completeness (all available data plot- 

 ted). 



e. Entry of late and off-time reports. 



f. In case of ships, proper location. 



12. There are inks of several different colors 

 which can be used when plotting a map to indi- 

 cate the types of data plotted. Although no 

 standard set of colors exists in the Navy, and 

 the colors used are normally determined lo- 

 cally, the following colors are recommended: 



a. Black or blue-black — On- time data or 

 blocks of off-time data (so indicated 

 in the msp legend). 



b. Red — Gradient winds and off-time data. 



c. Green— Data that are entered after the 

 map has been plotted. 



13. Be sure to plot the past positions of 

 pressure centers and fronts on the map. The 

 past positions of the pressure centers are in- 

 dicated by an X circumscribed by a circle with 

 the date and time placed immediately above. 

 The date is indicated by two numbers followed 

 by a colon or solidus (/) indicating the day of 

 the month. The second two numbers indicate 

 the time of data to the nearest whole hour GMT 

 preceding the time of the appropriate map. 

 Thus, 1200Z on the 20th day of the month is 

 entered as 20:12Z (or 20/12Z). 



SHIPBOARD CODE PLOTTING. — At sea there 

 is a lack of the close network of land reports, 

 and a single ship report may be the only one 

 in a vast area. A single ship report, too, may 

 be the only one giving an indication of a de- 

 veloping tropical storm which may be heading 



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