Effective midflame wind speedn. The magnitude of the resultant spread vector expressed as an equivalent noslope midflame wind speed.
The effective midflame wind speed is calculated in an algebraic equation involving slope steepness, wind speed, and wind direction. In the Rothermel (1972) surface fire spread model, the effect of midflame wind speed is expressed as the wind coefficient, and the effect of slope steepness is expressed as the slope factor.
