[Prodigal Son]

Is that coloration sand that is spread/blown laterally or vertically? Looks almost like a vertical cloud.

[Guillermo]

I wonder if those black border lines are there in real life?

[Ichneumon]

Is that coloration sand that is spread/blown laterally or vertically? Looks almost like a vertical cloud.

Laterally. The apparent "verticality" is just an optical illusion.

[!1776!]

Is that coloration sand that is spread/blown laterally or vertically? Looks almost like a vertical cloud.

Both, actually. The vertical motion of the storm lifts the sand vertically, and the winds advect the sand laterally.

A picture at:

http://www.osei.noaa.gov/IOD/OSEIiod.jpg

has some arrows to point out the sand.