Stable and strong stratification is a common phenomenon in the atmosphere,
oceans and lakes. Owing to their importance for the understanding of
geophysical flows, stratified flows have been investigated in many
theoretical, experimental and numerical studies. We have carried out
direct numerical simulations of stably and strongly stratified turbulent
flows and interpreted the results on basis of a scaling analysis of the
governing equations. The analysis suggests that there are two different
strongly stratified regimes and this is confirmed by the numerical
simulations.
