Values of U can be calculated for various windspeeds at (20+H) ft over single stratum 

 fuels. Using equation (2), we find: 



1 + 0.36H/H 



'20+H 



Jin 



0.13H ^ 



Hp/H + 0.36 



(9) 



The graph of figure 2 can be used to establish the ratio of the "midflame" windspeed to 

 the windspeed 20 ft over the vegetation cover for various fuel heights H and flame 

 extensions H^. 



LU 

 > 



O 



O 



LlJ 

 UJ 

 D_ 



o 



<; 



LlJ 

 > 



1.0 



0.8 



±0.6 



0.4 - 



E 0.2 - 



1 = FLAME EXTENSION ABOVE BED 

 HEIGHT OF FUEL BED 



1 



1 2 3 4 5 



HEIGHT OF FUEL BED (VEGETATION COVER), FT 



Fig. 2. — Average windspeed acting on a flame extending above a uniform surface fuelbed 

 layer (vegetation cover), due to log windspeed variation. 



5 



