TABLE 24 (Cont'd) 



WW = 20-29 Precipitation, fog, ice fog or tliunderstorm at the station during tlie preced- 

 ing hour but not at the time of observation 



Code figure 



WW 



20 Drizzle (not freezing) or snow grains 



21 Rain (not freezing) 



22 Snow 



23 Rain and snow or ice pellets, type (a) 



24 Freezing drizzle or freezing rain 



25 Shower(s) of rain 



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



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



28 Fog or ice fog 



29 Thunderstorm (with or without precipitation) 



not falling as shower(s) 



WW = 30 -39 Duststorm, sandstorm, drifting or blowing snow 



WW 



30 



31 

 32 



33 

 34 

 35 



Slight or moderate dust- 

 storm or sandstorm 



- has 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 



- no appreciable change during the 

 preceding hour 



- has begun or has increased during 

 the preceding hour 



36 Slight or moderate blowing snow 1 ,, , /,. , , ,^ 

 „, ,, , .,^. > generally low (below eye level) 



37 Heavy driftmg snow | 



Severe duststorm or 

 sandstorm 



38 Slight or moderate blowing snow 



39 Heavy blowing snow 



generally high (above eye level) 



WW = 40 -49 Fog or ice fog at the time of observation 



WW 



40 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 



41 Fog or ice fog in patches 



42 Fog or ice fog, sky visible \ has become thinner during the preceding 



invisible / hour 



43 Fog or ice fog, sky ir 



Hail, ice pellets, type (b), snow pellets. French : grele, gresil ou neige roul^e. 



71 



