The flow field induced by a sphere oscillating horizontally in a linea
rly stratified fluid is studied using a series of laboratory experimen
ts. The resulting flows are shown to depend on the Stokes number beta,
the Keulegan-Carpenter number KC and the internal Froude number Fr. F
or Fr less than or similar to 0.2, it is shown that the nature of the
resulting flow field is approximately independent of Fr and, based on
this observation, a flow regime diagram is developed in the (beta, KC)
-plane. The flow regimes include: (i) fully-attached flow; (ii) attach
ed vortices; (iii) local vortex shedding; and (iv) standing eddy pair.
An internal-wave flow regime is also identified but, for such flows,
the motion field is a function of Fr as well. Some quantitative measur
es are given to allow for future comparisons of the present results wi
th analytical and/or numerical models. Wherever possible, the results
are compared with the experiments of Tatsuno & Bearman (1990) on right
circular cylinders oscillating in homogeneous fluids.