24 PROCEEDINGS OF THE NATIONAL MUSEUM 



04 Visibility reduced by smoke, 



e.g., veldt or forest fires, 

 industrial smoke, or vol- 

 canic ashes. 



05 Dry haze. 



06 Widespread dust in suspen- 



sion in the air, not raised 

 by wind at or near the ship 

 at the time of observation. 



07 Dust or sand raised by wind 



at or near the ship at the 

 time of observation, but no 

 well-developed dust 

 devil (s), and no duststorm 

 or sandstorm seen. 



08 Well-developed dust devil(s) 



seen at or near the ship 

 within last hour, but no 

 duststorm or sandstorm. 



09 Duststorm or sandstorm within 



sight of the ship or at the 

 ship during the last hour. 



10 Light fog (visibility 1,100 



yards or more). 



Haze, dust, sand, or 

 smoke. 



11 Patches of. 



12 More or less continuous. 



13 Lightning visible, no thunder 



heard. 



14 Precipitation within sight but 



not reaching surface at the 

 ship. 



15 Precipitation within sight, 



reaching surface, but dis- 

 tant (i.e., estimated to be 

 more than 3 miles from the 

 ship). 



16 Precipitation within sight, 



reaching surface, near to 

 but not at the ship. 



Shallow fog at the ship not 

 deeper than about 33 

 feet. 



