Which is the third layer of the atmosphere as listed?

Which is the third layer of the atmosphere as listed?

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

Answer: (A)

The question tests how atmospheric layers are ordered and identified. The Stratosphere is the layer directly above the Troposphere and below the Mesosphere, and it’s known for warming with height due to ozone absorbing UV radiation. In many standard schemes the sequence is Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere, which would place the third layer as Mesosphere. The answer here reflects the particular list used in this item, where the Stratosphere is presented as the third layer. The key point to remember is that the Stratosphere is a distinct, stable layer above the Troposphere with increasing temperature with altitude and contains the ozone layer. The Ionosphere is a upper-atmosphere region that’s not typically treated as one of the main five layers, which can add confusion if different resources classify it differently.

The question tests how atmospheric layers are ordered and identified. The Stratosphere is the layer directly above the Troposphere and below the Mesosphere, and it’s known for warming with height due to ozone absorbing UV radiation. In many standard schemes the sequence is Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere, which would place the third layer as Mesosphere. The answer here reflects the particular list used in this item, where the Stratosphere is presented as the third layer. The key point to remember is that the Stratosphere is a distinct, stable layer above the Troposphere with increasing temperature with altitude and contains the ozone layer. The Ionosphere is a upper-atmosphere region that’s not typically treated as one of the main five layers, which can add confusion if different resources classify it differently.