Which atmospheric layer is closest to Earth's surface?

Which atmospheric layer is closest to Earth's surface?

• A. Stratosphere
• B. Troposphere
• C. Mesosphere
• D. Thermosphere

Answer: (B)

The layer closest to Earth’s surface is the troposphere, where almost all of the atmosphere’s mass sits and where weather happens. It extends from the ground up to roughly 8–15 kilometers, depending on latitude and season. In this region, temperature generally decreases with altitude, which drives air to rise and form clouds, rain, and winds—the dynamic processes we associate with weather. The top boundary is the tropopause, separating it from the layer above. Above the troposphere lies the stratosphere, which contains the ozone layer and where temperature tends to rise with altitude due to ozone absorbing ultraviolet radiation. Higher still is the mesosphere, characterized by very cold temperatures and where most meteors burn up. The outermost layer, the thermosphere, has extremely thin air and can reach high temperatures from solar radiation, even though it would feel very cold because of the sparse air.

The layer closest to Earth’s surface is the troposphere, where almost all of the atmosphere’s mass sits and where weather happens. It extends from the ground up to roughly 8–15 kilometers, depending on latitude and season. In this region, temperature generally decreases with altitude, which drives air to rise and form clouds, rain, and winds—the dynamic processes we associate with weather. The top boundary is the tropopause, separating it from the layer above.

Above the troposphere lies the stratosphere, which contains the ozone layer and where temperature tends to rise with altitude due to ozone absorbing ultraviolet radiation. Higher still is the mesosphere, characterized by very cold temperatures and where most meteors burn up. The outermost layer, the thermosphere, has extremely thin air and can reach high temperatures from solar radiation, even though it would feel very cold because of the sparse air.