CONTENTS 



Page 



Introduction IX 



Chapter 



I General Instructions 1-12 



Time of Observation 3 



Ship's Weather Observations --Form 615-5 3-6 



Radio Transmission of Weather Observations 6-9 



Ordering Supplies 9 



Weather Bureau Port Offices 10-12 



II Identification Data 13-17 



General 15 



Day of Month 15 



Day of Week (Y) 15 



Octant of Globe (Q) 15-16 



Latitude (La^aLa) 16 



Longitude (LqLqLq) 16 



Greenwich Civil Time (GG) 16-17 



Ship's Course (Dg) 17 



Ship's Speed (vg) 17 



III Wind 19-28 



General 21 



Wind Direction 21 



Wind Speed 23 



True Wind from the Apparent Wind 23-27 



Wind Shifts 27-28 



IV Visibility 29-33 



General 33 



Determination of Visibility 31-32 



Coding and Entry of Visibility Data (VV) on 



Form 615-5 32 



V Weather 3 5-44 



General 37 



Thunderstorms and Lightning 37 



Waterspouts and Squalls 38 



Precipitation 38-40 



Fog and Rime 41 



Eaze, Smoke, and Dust 41 



Miscellaneous 41 



Present Weather (ww) 41-42 



Past Weather (W) 42-44 



