  Let G be an almost simple group over an algebraically closed field k of
characteristic zero, let g be its Lie algebra and let B be a Borel subgroup of
G. Then B acts with finitely many orbits on the variety N_2 of the nilpotent
elements in g whose height is at most 2. We provide a parametrization of the
B-orbits in N_2 in terms of subsets of pairwise orthogonal roots, and we
provide a complete description of the inclusion order among the B-orbit
closures in terms of the Bruhat order on certain involutions in the affine Weyl
group of g.
