g. Wind Observations . 



(1) Windspeed (Blocks 26 and 27) . A Dwyer wind meter is used to 

 determine windspeed. The instrument is held slightly above head level, and 

 slowly rotated in a 360° arc until the maximum windspeed is found. The meter 

 contains two scales. When the windspeed is less than 10 miles (16.1 kilo- 

 meters) per hour, the hole on the top of the meter should be open and the 

 windspeed is read from the left scale (Fig. 12). The two holes at the bottom 

 on the back of the meter must be kept clear to obtain an accurate reading. 

 When the windspeed exceeds 10 miles per hour (i.e., when the windspeed indi- 

 cator ball in the meter exceeds the top of the scale) the hole on top of the 

 wind meter should be closed by placing a finger over it (Fig. 13). The wind- 

 speed is then read from the right scale on the meter. Windspeed is recorded 

 to the nearest mile per hour with an average windspeed selected by watching 

 the movement of the indicator ball. 



Figure 12. Using Dwyer wind meter for windspeed 

 less than 10 miles per hour. 



-*? 



Figure 13. Using Dwyer wind meter for windspeed 

 greater than 10 miles per hour. 



17 



