I have read in several places, including in the R Douglas Hurt book The Dust Bowl: A Social & Agricultural History that in the middle 1930s the Kansas Academy of Sciences classified dust storms into seven types of three general varieties (rectilinear, rotational, and ebullitional: ostensibly dust blowing in a straight line, the storm rolling horizontally because of wind shear, and having a boiling, cumuliform appearance due to convection, instability &c, respectively) -- and goes on to mention the two ends of the scale, the sirocco-driven sand blow and the full-scale funnel storm that throws the dirt into the upper troposphere . . . does anyone know what the other five types are? Is this paper accessible online somehow I have not been able to find yet? Thank you for your input.