INSTRUCTIONS TO MARINE METEOROLOGICAL OBSERVERS 39 



00 

 01 

 02 

 03 

 04 

 05 

 06 

 07 

 08 

 09 

 10 

 11 

 12 

 13 

 14 

 15 

 16 

 17 



18' 

 19 



20 

 21 

 22 

 23 

 24 

 25 

 26 

 27 

 28 

 29 



Code table for idio (present weather) 



ABBEEVIAIED DESCRIPTION OF SKY AND SPECIAL PHENOMENA 



Cloudless. 

 Partly cloudy. 

 Cloudy. 

 Overcast. 



Low fog, on ground or over sea. 



Haze (but visibility greater than 2,000 m., 2,200 yds). 

 Dust devils seen. 

 Distant lightning. 



Light fog (visibility between 1,000 and 2,000 m., 1,100 and 2,200 yds). 

 Fog at a distance, but not at the ship. 

 Precipitation within sight. 

 Thunder, without precipitation at the ship. 

 Dust storm within sight, but not at the ship. 

 Ugly, threatening sky. 

 Squally weather. 



Heavy squalls | ^ 3 ^^^^^ 

 Waterspouts seen J 



Visibility reduced by smoke (industrial, grass or forest fires), or vol- 

 canic ashes. 

 Dust storm (visibility greater than 1,100 yards). 

 Signs of tropical storm (hurricane). 



PRECIPITATION IN LAST HOUR BUT NOT AT TIME OF OBSERVATION 



Precipitation (rain, drizzle, hail, snow, or sleet) 



Drizzle ] 



Rain 



Snow I 



Rain and snow, mixed) 



Rain shower (s). 



Snow shower (s). 



Hail or rain and hail shower 



Slight thunderstorm. 



Heavy thunderstorm. 



mother than showers 



(s). 



In last hour but not at 

 time of observation. 



DUST STORMS AND STORMS OF DRIFTING SNOW 

 (Visibility less than 1,000 in., 1,100 yards) 



30 Dust or sand storm. 



31 Dust or sand storm has decreased. 



32 Dust or sand storm, no appreciable change. 



33 Dust or sand storm has increased. 



34 Line of dust storms. 



35 Storm of drifting snow. 



36 Slight storm of drifting snow 1, 



37 Heavy storm of drifting snow I ' 



38 Slight storm of drifting snowj 



39 Heavy storm of drifting snow ! 



enerally low. 

 generally high. 



FOG 



(Visibility less tban 1,000 m., 1,100 yards) 



but not at time of observation. 



40 Fog. 



41 Moderate fog in last hour 



42 Thick fog in last hour 



43 Fog, sky discernible v, „„ , ^^„ „ +i • -, ■ 1 , , 



44 Fog; sky not discernible l^''^^ ^^^'O™^ tl"""*^^- ^^"^^^ ^^^^"^ l^'^^"'" 



45 Fog, sky discernible ) • 1 1 i 1-1^1 



46 Fog, sky not discernible f ^« '^PPreciable change during last hour. 



47 Fog, sky discernible 



48 Fog, sky not discernible 



49 Fog in patches. 



\ 



has begun or become thicker during last hour. 



