The Earth’s atmosphere is divided into three main layers: Troposphere, Stratosphere, and which other layer?

The Earth’s atmosphere is divided into three main layers: Troposphere, Stratosphere, and which other layer?

• A. Mesosphere
• B. Ionosphere
• C. Thermosphere
• D. Exosphere

Answer: (A)

The main idea is how the atmosphere is organized by height and temperature. Starting from the surface, the troposphere is where weather happens and temperatures generally drop with altitude. Above it lies the stratosphere, where temperatures rise with height due to ozone absorbing UV radiation. The next major region is the mesosphere, which sits above the stratosphere and below the thermosphere; here temperatures fall again with altitude and it’s where most meteors burn up as they enter the atmosphere. That’s why the third major layer is the mesosphere. The ionosphere isn’t one of the traditional primary layers; it’s a region of ionized particles that spans parts of the upper atmosphere and thermosphere/mesosphere and is important for radio communications, but it isn’t counted as a distinct main layer in this basic three-layer framework. The thermosphere and exosphere are higher than the mesosphere.

The main idea is how the atmosphere is organized by height and temperature. Starting from the surface, the troposphere is where weather happens and temperatures generally drop with altitude. Above it lies the stratosphere, where temperatures rise with height due to ozone absorbing UV radiation. The next major region is the mesosphere, which sits above the stratosphere and below the thermosphere; here temperatures fall again with altitude and it’s where most meteors burn up as they enter the atmosphere. That’s why the third major layer is the mesosphere.

The ionosphere isn’t one of the traditional primary layers; it’s a region of ionized particles that spans parts of the upper atmosphere and thermosphere/mesosphere and is important for radio communications, but it isn’t counted as a distinct main layer in this basic three-layer framework. The thermosphere and exosphere are higher than the mesosphere.