INSTRUCTIONS TO MARINE METEOROLOGICAL OBSERVERS Ql 



Figure 30. — Symbols (abridged) for showing state of weather. 



which the Avind blows. When cahn, no aiTOw 



The direction of the wind is shown by an arrow drawn through 

 the station circle. The arrow flies with the wind ; that is, the head 

 of the arrow points in the direction toivard which the wind is blow- 

 ing. A northwest wind, for example, blows from the northwest 

 toward the south- 

 east and the head of 

 the arrow slionld 

 point toward the 

 southeast. To save 

 time, the head of 

 tlie arrow is omitted 

 on some maps and 

 only the shaft is 

 drawn, pointing in 

 the direction from 

 is drawn. 



The force of tlie wind is shown by barbs (or feathers) on the shaft 

 of the arrow, the number of feathers being equal to the number for 

 wind force on the Beaufort scale. 



If preferred, wind force to lialf scale may be indicated by full 

 barbs and half barbs. The full barb represents two units of force on 

 the Beaufort scale and the half barb one unit ; for example, two full 

 barbs and one half barb together indicate force 5. If this practice 

 is adopted, the barbs (or feathers) are all drawn on the same side 

 of the arrow shaft, which is the right side wdien facing in the direc- 

 tion from which the wind is blowing. The use of full- and half- 

 length barbs (Beah- 

 fort half scale) was 

 adopted by the 

 United States 

 Weather Bureau, 

 effective Januarv 1, 

 1937. 



Examples of dif- 

 ferent methods of 

 making entries of 

 wind direction and 

 force, with and 

 witliout station cir- 

 cles and arrow- 

 heads, are shown in 

 figure 31. 



Various methods 

 of e n t r y (arrow- 

 heads, state of 

 weather, etc.) are shown m order that the shipmaster may adopt 

 practices suited to his needs. Wliatever practice is adopted should 

 preferably be uniformly used on all his maps. 



After the entry of wind direction and force has been made, with 

 state of weather when required, figures are placed in a convenient 

 location at the right of the station position to show barometric 

 pressure at time of observation and, if desirable, temperatures of air 

 and water. In the International Code for ships' weather reports, 



Figure 31. — A. Wind northeast, force 4, weather clear (with 

 arrowhead). B. Wind northwest, force 5, raining (arrow- 

 head omitted). C. Wind north, force 7 (state of weather 

 not shown ; arrowhead omitted ; dot sliows location of ob- 

 serving station or sliip). D. Wind southeast, force 3. 

 E. Wind southwest, force 1, snowing. F. Wind south- 

 east, force 10, clear. 



.n672°38- 



