Which altitude would you be most likely to feel the polat jet stream?

The polar jet stream is typically found at altitudes between 30,000 and 40,000 feet (about 9,000 to 12,000 meters) in the atmosphere. It forms at the boundary between cold polar air and warmer air from the mid-latitudes. Travelers at cruising altitudes in commercial airliners, usually around 30,000 to 40,000 feet, are most likely to encounter the polar jet stream. Its influence can lead to significant changes in weather patterns and flight conditions.