Tropopause is the boundary between which atmospheric layers?

• A. The troposphere and the stratosphere
• B. The stratosphere and the mesosphere
• C. The mesosphere and the thermosphere
• D. The ionosphere and the exosphere

Answer: (A)

The boundary between the troposphere and the stratosphere is called the tropopause. It marks the top of the lowest atmospheric layer where most weather, clouds, and turbulence occur, and the start of the next layer where the temperature behavior changes. In the troposphere the temperature generally decreases with height, but in the stratosphere the temperature starts to rise with height due to the absorption of UV radiation by ozone, creating a stable layer above the tropopause. The height of this boundary varies with latitude and season, roughly 8–12 km over the poles and up to about 16–20 km near the equator. Other layer boundaries exist (such as the stratopause between the stratosphere and mesosphere, and the mesopause between the mesosphere and thermosphere), but the tropopause specifically separates the troposphere from the stratosphere.