Question: is there a jet stream in the southern hemisphere

Answer: Yes, The strongest jet streams are the polar jets, at 9--12 km (30,000--39,000 ft) above sea level, and the higher altitude and somewhat weaker subtropical jets at 10--16 km (33,000--52,000 ft). The Northern Hemisphere and the Southern Hemisphere each have a polar jet and a subtropical jet. The northern hemisphere polar jet flows over the middle to northern latitudes of North America, Europe, and Asia and their intervening oceans, while the southern hemisphere polar jet mostly circles Antarctica all year round.