[PATTERSON] CANADIAN STANDARP ANEMOMETER 



Table VIII 



95 



The Canadian anemometer registers a velocity a little less than 

 the most probable maximum velocity that occurs in gusts and the 

 higher the velocity the more nearly does it approach this value. 

 Again Simpson (loc. cit.) has given what he calls the probable mean 

 velocity in the gust, as 



V=-5 + l-2v 



where V is the probable mean velocity and v is the mean wind velocity. 

 Their values are also given in the table and they show that for all 

 winds above 50 miles per hour the Canadian anemometer registers 

 a greater velocity than the probable mean velocity in the gusts. 



The Kew standard anemometer (9" cups on 24" arms) has a 

 factor 2-2 instead of 3, and expressing the equation Vg = 3 + l-26 Vk 

 where Vg is the most probable gust velocity and Vk the mean hourly 

 velocity in terms of the indicated velocity on the Kew anemometer 

 we have 



Vg = 3+-92 Vk; Vk = velocity given by Kew anemometer. 



For all practical purposes this may be written 



Vg = Vk 

 and we have the important result that the Kew Standard Anemometer 

 records the most probable maximum velocity in gusts. 



Summary 



1. The comparison of the Canadian Standard Anemometer with 

 the Dines Pressure Tube Anemometer has shown that the factor "3" 

 is not correct and the factor is variable. . 



