AEROGRAPHER'S MATE 3 & 2 



8. Light wind. The wind is considered to 

 be light when the speed is six knots or less. 



WIND MEASUREMENTS 



There are four qualities of the wind that 

 the observer must determine; they are wind 

 direction, wind speed, character, and shifts. 

 Instructions for determining these qualities of 

 the wind are contained in the following para- 

 graphs. 



The instruments used by the Navy are the 

 direct reading type (indicating or recording) 

 and are described later in this chapter. 



Wind Direction 



Wind direction is observed for a 1-minute 

 interval with reference to true north and in 

 10°-increments in a clockwise direction from 

 true north. When the air is not in motion, 

 the wind is said to be CALM. When instruments 

 for measuring the wind direction are not avail- 

 able or are inoperative, estimate the direction 

 by observing a wind cone or tee, movement of 

 trees, smoke, or by facing into the wind in 

 an unsheltered area. 



Do not use the movement of clouds, regard- 

 less of how low the clouds are, in estimating 

 the surface wind direction. 



Wind Speed 



Determine speed of the surface wind to the 

 nearest knot. In general, observed wind speeds 

 are a 1-MINUTE AVERAGE. So far as possible, 

 the average wind speed observation should not 

 be made during a peak or lull in gusty winds 

 or squalls. 



Where wind speed instruments are tem- 

 porarily unrepresentative or not available, 

 estimated speed (including gustiness and squall 

 data) may be determined by use of Appendix VI. 



Character and Shifts 



The character and shifts of the wind are 

 determined by examining the wind speed 

 indicator/ recorder to determine if the required 

 criteria have been met to report the phenomena. 



FORMS 



Several types of forms are used to record 

 wind data. Some were previously mentioned, 

 such as the MF1-10 shore form, and the 

 NWSC 3140/8 ship form, also recording rolls for 

 the UMQ-5( ) and GMQ-29( ). 



MF1-10 Entries 



Although the following descriptions of wind 

 element entries are correct, they are brief 

 and the Aerographer should refer to the 

 Federal Meteorological Handbook No. 1 for a 

 more complete and detailed description of 

 the proper procedures. 



WIND DIRECTION (COL . 9) . — Enter the wind 

 direction to the nearest tens of degrees. Use 

 2 digits as shown in table 3-1. Enter "00" when 

 the wind is calm. Whenever either the reported 

 wind direction, speed, speed of gusts or squalls 

 is estimated, prefix the direction with an 



WIND SPEED (COL. 10). — Enter the wind 

 speed in knots. For calm wind enter "00". 

 When the speed exceeds 99 knots, enter only 

 the tens and units figures and add 50 to the 

 wind direction in column 9; e.g., 112 knots from 

 270° 7712. 



WIND CHARACTER (COL. 11). — Enter gusts 

 by using the symbol "G" followed immediately 

 by the peak speed of gusts observed during the 

 past 10 minutes. Report squalls by the symbol 

 "Q" followed immediately by the peak squall 

 wind observed during the past 10 minutes. 



These are reported when they occur 

 regardless of the type of wind equipment 

 utilized. 



WIND SHIFTS AND VARIABLE WIND DATA 

 (COL. 13). — A wind shift is always reported 

 when it occurs. To report a wind shift, enter 

 in column 13 the contraction "WSHFT" followed 

 by the time the wind shift began in minutes 

 past the hour using two digits (e.g., WSHFT 37). 

 When the shift is reasonably certain to be 

 associated with a frontal passage, include the 

 contraction "FROPA" immediately after the 

 time (e.g., WSHFT 37 FROPA). If the remark 

 containing this data Is not transmitted via 

 longline teletype, the data will then be included 



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