unit : m/zs<br>
range : [1.5,6]<br>
niminal value : 2.8 & m/s<br>
w_B=wbsrf+wbmax/[1.+500/(P_s-P_{LFC})], where P_s and P_{LFC} are the surface and "Level of Free Convection" pressure in hPa. <br>