Abstract : The present report is a preliminary attempt to distinguish various flow regimes in a jet flow of a stratified fluid. It points out the difficulties associated with the linear stratification model in an unbounded fluid. It seems that the modeling mechanism of generating linear stratification is quite important, and that the flow structure can change according to whether bounding walls are used to generate the stratification thermally or not. Careful evaluation of this aspect of the interaction both experimentally and analytically is need to clarify the meaning of linear stratification in an unbounded fluid.