Which staement about jet streams are true?

Jet streams are fast-flowing air currents located in the upper atmosphere, typically at altitudes of 30,000 to 40,000 feet. They are primarily found near the boundaries of major air masses, such as between polar and tropical air. Jet streams influence weather patterns and can affect flight routes, with their direction and strength varying seasonally. They play a crucial role in the movement of storms and can lead to significant temperature differences across regions.