This paper presents a numerical study in which the evolution of vortices in
a stratified fluid is compared to the evolution of two-dimensional vortice
s. The influence of the Reynolds number and the Froude number are investiga
ted, for the evolution of axisymmetric vortices, for their azimuthal instab
ility and for the subsequent formation of tripoles. It is found that due to
radial diffusion axisymmetric vortices with various initial vorticity prof
iles all evolve towards the same profile. This evolution reduces the growth
of azimuthal instabilities which may lead to the formation of a tripole. F
or vortices in a stratified fluid the effect of the ambient stratification
on the evolution of the vortices is investigated. It is found that a proces
s of vortex stretching, which becomes more pronounced for increasing Froude
numbers, leads to a weaker tripole formation.