According to the search results, the strongest jet streams are the polar jets around the polar vortices, located at 9-12 km (5.6-7.5 mi; 30,000-39,000 ft) above sea level, and the higher altitude and somewhat weaker subtropical jets at 10-16 km (6.2-9.9 mi; 33,000-52,000 ft) . Polar jet streams are typically located near the 250 hPa (about 1/4 atmosphere) pressure level, or seven to twelve kilometers (23,000 to 39,000 ft) above sea level, while the weaker subtropical jet streams are much higher, between 10 and 16 kilometers (33,000 and 52,000 ft) . The jet streams form near breaks in the tropopause, at the transitions between the polar, Ferrel, and Hadley circulation cells, and their circulation, with the Coriolis force acting on those masses, drives the jet streams. The polar jet stream is most commonly found between latitudes 30° and 60° (closer to 60°), while the subtropical jet streams are located close to latitude 30° .