Jet streams are high-velocity winds that occur in which atmospheric layer?

• A. Stratosphere
• B. Mesosphere
• C. Upper Troposphere
• D. Exosphere

Answer: (C)

Jet streams form where there’s a strong horizontal temperature difference between air masses and the rotation of the Earth helps shape those winds into narrow, fast bands. This combination pushes these winds to very high speeds in a relatively thin layer of the atmosphere. Most of this happens in the upper part of the troposphere, near the tropopause, where weather systems are driven and the air is thin enough to allow rapid speeds. That’s why the jet streams are described as occurring in the upper troposphere. While they can extend toward the lower stratosphere, they aren’t characteristic of the stratosphere, mesosphere, or exosphere.