Which atmospheric layer lies nearest the Earth's surface?

Which atmospheric layer lies nearest the Earth's surface?

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

Answer: (B)

The layer closest to Earth's surface is the troposphere, the part of the atmosphere that contains most of the air we breathe and all weather phenomena. It stretches from the ground up to an upper boundary called the tropopause, which sits roughly at 8 to 15 kilometers above the surface depending on latitude and season. Because it holds the bulk of the atmosphere’s mass, it’s the first region you encounter as you move away from the surface. In this layer, heat transfer and movement of air are dominated by convection. That’s why clouds, rain, and winds form here. Temperature generally drops as you go higher in the troposphere, which helps drive vertical air motions that fuel weather systems. Above the troposphere lies the stratosphere, where temperature starts to rise with altitude due to the absorption of ultraviolet radiation by the ozone layer, making this layer more stable and stratified. Even higher are the thermosphere and exosphere, where the air becomes extremely thin and temperatures can be very high in terms of energy per molecule, though that heat isn’t felt the same way as in denser air.

The layer closest to Earth's surface is the troposphere, the part of the atmosphere that contains most of the air we breathe and all weather phenomena. It stretches from the ground up to an upper boundary called the tropopause, which sits roughly at 8 to 15 kilometers above the surface depending on latitude and season. Because it holds the bulk of the atmosphere’s mass, it’s the first region you encounter as you move away from the surface.

In this layer, heat transfer and movement of air are dominated by convection. That’s why clouds, rain, and winds form here. Temperature generally drops as you go higher in the troposphere, which helps drive vertical air motions that fuel weather systems.

Above the troposphere lies the stratosphere, where temperature starts to rise with altitude due to the absorption of ultraviolet radiation by the ozone layer, making this layer more stable and stratified. Even higher are the thermosphere and exosphere, where the air becomes extremely thin and temperatures can be very high in terms of energy per molecule, though that heat isn’t felt the same way as in denser air.