Temperature decreases with height in the

Step 1: Analyze the question The question asks which layer of the atmosphere has temperature that decreases as you go higher.

Step 2: Concept: layers of the atmosphere The atmosphere has layers, and temperature changes differently in each one:

| Layer | Temperature trend with height | |---|---| | Troposphere (0 to about 12 km) | Decreases (about 6.5°C per 1,000 m) | | Stratosphere (about 12 to 50 km) | Increases (the ozone layer absorbs UV radiation) | | Mesosphere (about 50 to 80 km) | Decreases | | Thermosphere/Ionosphere (about 80 to 600 km) | Increases sharply | | Exosphere (above about 600 km) | Very high, and gradually merges into space |

Step 3: Apply it to the options

• A. Stratosphere: Temperature rises with height because ozone absorbs ultraviolet rays. Wrong.
• B. Troposphere: The air is heated mainly from the ground, which absorbs solar radiation and warms the air above it. The farther you go from the ground, the cooler it gets. This is the normal lapse rate. Correct.
• C. Ionosphere: It lies within the thermosphere, where temperature increases with height. Wrong.
• D. Exosphere: The outermost layer, where temperature is high and the air is extremely thin. Wrong.

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Exam tip: Remember the pattern "Down, Up, Down, Up" for the layers from the ground upward: Troposphere ↓, Stratosphere ↑, Mesosphere ↓, Thermosphere ↑. Also remember that the troposphere is where we live and where weather happens, and it is the only one of the lower layers heated from below, which is why it gets colder as you climb. This is why mountain tops like Obudu Plateau are cooler than the lowlands.