Table B-1. Descriptive terms for present weather (extracted from WMO Code 4677) 



\i 01 



02 

 03 

 (04 

 05 

 06 



07 



characteristic change of the state of sky during the 

 past hour 



Code figure 



00 Cloud development not observed or not ob- 

 ttfg servable 



Clouds generally dissolving or becoming less de- 

 veloped I 



State of sky on the whole unchanged 



Clouds generally forming or developing j 



Visibility reduced by smoke, e.g. veldt or forest fires, industrial smoke or volcanic ashes 



Haze 



Widespread dust in suspension in the air, not raised by wind at or near the station at the time of obser- 

 vation 



Dust or sand raised by wind at or near the station at the time of observation, but no well developed dust 

 whirl(s) or sand whirl(s), and no duststorm or sandstorm seen 



Well developed dust whirl(s) or sand whirl(s) seen at or near the station during preceding hour or at the 



time of observation, but no duststorm or sandstorm 

 Duststorm or sandstorm whithin sight at the time of observation or at the station during the preceding 

 hour 



Mist 



Patches of ] shallow or ice fog at the station, whether on land 



More or less [ or sea, not deeper than about 2 metres on land or 10 



continuous J metres at sea 



Lightning visible, no thunder heard 



Precipitation within sight, not reaching the ground or the surface of the sea 



Precipitation within sight, reaching the ground or the surface of the sea, but distant (i.e. estimated to be 

 more than .5 km) from the station 



Precipitation within sight, reaching the ground or the surface of the sea, near to, but not at the station 



Thunder storm, but no precipitation at the station 



16 

 17 

 18 

 19 

 20 

 21 

 22 

 23 

 24 

 25 

 26 

 27 

 28 

 29 

 30 

 31 

 32 

 33 

 34 

 35 

 36 

 37 

 38 

 39 

 40 



41 

 42 

 43 

 44 

 45 

 46 

 47 

 48 

 49 



at or within sight of the station during the preceding 

 hour or at the time of observation 



not falling as shower(s) 



Squalls 



Funnel cloud(s)*) 



Drizzle (not freezing) or snow grains 



Rain (not freezing) 



Snow 



Rain and snow or ice pellets, type (a) (sleet) I 



Freezing drizzle or freezing rain j 



Shower(s) or rain 



Shower(s) of snow, or of rain and snow 



Shower(s) of hail,** or of rain and hail** 



Fog or ice fog 



Thunderstorm (with or without precipitation) 



ihas decreased during the preceding hour 

 no appreciable change during the preceding hour 

 has begun or has increased during the preceding hour 

 ( has decreased during the preceding hour 

 Severe duststorm or sandstorm \ no appreciable change during the preceding hour 



( has begun or has increased during the preceding hour 

 Slight or moderate drifting snow 

 Heavy drifting snow 

 Slight or moderate drifting snow- 

 Heavy drifting snow 

 Fog or ice fog at a distance at the time of observation, but not at the station during the preceding hour, 



the fog or ice fog extending to a level above that of the observer 

 Fog or ice fog in patches 

 Fog or ice fog, sky visible 

 Fog or ice fog, sky invisible 

 Fog or ice fog, sky visible 

 Fog or ice fog, sky invisible 

 Fog or ice fog, sky visible \ has begun or has become thicker during the preceding 



Fog or ice fog, sky invisible J hour 



Fog, depositing rime, sky visible 

 Fog, depositing rime, sky invisible 



generally low (below eye level) 

 generally high (above eye level) 



has become thinner during the preceding hour 

 no appreciable change during the preceding hour 



B-2 



