In this study some experimental results are given to demonstrate that the density stratification is the main reason for the appearance of cloud vortex trails over ocean islands. Evidences are given that the similarity of these vortex trails to von Karmen streets may not go beyond the general streak-line pattern. The experimental results reveal the three-dimensional vortex shedding structure when a sphere is towed at a constant velocity through a stratified fluid. It is found that for small or moderate stratification and Reynolds numbers in the range from l03 to l04 the vortex is shed three-dimensionally. The stratification however quickly and effectively inhibits the vertical motion and the initially turbulent wake collapses and reveals the vertically oriented portion of the vortex structure, reminiscent of the two-dimensional vortex street behind a circular cylinder when viewed from above. Considerable insights are given concerning the vortex shedding and its structure in the wake of a three-dimensional body.