GED Science Practice 2025 - Free GED Science Practice Questions and Study Guide

The jet stream is typically found in the troposphere, which is the lowest layer of Earth's atmosphere. This layer extends from the Earth's surface up to about 8 to 15 kilometers (5 to 9 miles) high, depending on the location. The jet streams are fast-flowing, narrow air currents that play a crucial role in determining weather patterns and systems. They occur at high altitudes within the troposphere, where temperature differences between air masses create strong winds.

While the other options reference different layers of the atmosphere, they do not contain the jet stream. The mesosphere lies above the stratosphere, and while it does contain some aircraft and space phenomena, it is not where the jet stream operates. The stratosphere, although it does contain the ozone layer, is generally too stable for the jet streams, which are influenced by the temperature fluctuations and vertical mixing prevalent in the troposphere. The thermosphere is the highest layer, where the air is extremely thin and primarily contains ionized gases, making it an unlikely location for the jet stream's activity.