In which of the following layers in the atmosphere does temperature increase with altitude?

Analyze the question: It asks which atmospheric layer has temperature that rises as you go higher.

Concept: Temperature in the atmosphere

From the ground upward, the layers behave like this:

| Layer | Temperature trend with height | Reason | |---|---|---| | Troposphere | Decreases | Heated from the ground below; air gets colder with height (about 6.5°C per 1,000 m) | | Stratosphere | Increases | The ozone layer absorbs ultraviolet (UV) radiation from the sun and releases heat | | Mesosphere | Decreases | Little ozone to absorb radiation; this is the coldest layer | | Thermosphere | Increases | Absorbs very high-energy solar radiation | | Exosphere | Gradually merges into space | Very thin air, with few molecules to hold heat |

Solution, option by option:

• A. Troposphere: Temperature falls with altitude, so this is wrong.
• B. Ionosphere: This is not a separate thermal layer. It is a region of charged particles that overlaps the mesosphere and thermosphere. Temperature does rise in its upper part (the thermosphere), but it is not the standard layer the question is looking for.
• C. Stratosphere: Temperature rises with height because of ozone absorbing UV radiation. This is the classic answer.
• D. Exosphere: This is the outermost layer, where air is extremely thin and the idea of temperature is not meaningful in the usual sense, so it is not the best answer.

Answer: The stratosphere, option C.

Exam tip: Remember the pattern "Down, Up, Down, Up" for Troposphere, Stratosphere, Mesosphere, Thermosphere. Temperature falls, rises, falls, then rises again. Whenever WASSCE asks about temperature increasing in the lower atmosphere, think stratosphere and ozone.