Layers of the Earth’s atmosphere—identify the incorrect statement Which of the following statements about the troposphere, stratosphere, and mesosphere is WRONG for atmospheric science and environmental engineering practice?
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AThe concentric atmospheric layer just above the troposphere is the stratosphere, which is rich in ozone.
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BThe mesosphere is characterized by very low atmospheric pressure and low temperature.
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CThe troposphere is a dusty zone containing water vapour and clouds, where most weather occurs.
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DLong-distance radio waves are reflected back to Earth by the stratosphere.
Answer
Correct Answer: Long-distance radio waves are reflected back to Earth by the stratosphere.
Explanation
Introduction / Context:Understanding the structure of the atmosphere is fundamental in environmental engineering, air-pollution control, and radio communication. Each layer—troposphere, stratosphere, mesosphere, thermosphere/ionosphere—has distinct properties that influence weather, ozone chemistry, and the propagation of electromagnetic waves.
Given Data / Assumptions:
- Troposphere is the lowest layer, where most weather and clouds occur.
- Stratosphere lies above the troposphere and contains the ozone layer.
- Mesosphere lies above the stratosphere with low pressure and temperature.
- Long-distance high-frequency radio communication commonly relies on reflection/refraction by the ionosphere.
Concept / Approach:The correct identification hinges on which layer reflects radio waves used in long-distance communication. It is not the stratosphere but the ionosphere (part of the thermosphere) that affects radio propagation. The other listed statements about troposphere dust/clouds and stratospheric ozone are standard facts in atmospheric science.
Step-by-Step Solution:
Recognize that the stratosphere sits above the troposphere and is ozone-rich—this is true.Note that the mesosphere has low temperature and pressure—also true.Recall that long-distance radio reflection occurs in the ionosphere, not the stratosphere.Therefore, the statement attributing radio wave reflection to the stratosphere is wrong.Verification / Alternative check:Radio engineering and atmospheric references consistently describe the ionosphere (approximately 60–1000 km altitude) as the region responsible for reflecting/refracting HF radio waves, enabling beyond-line-of-sight communication.
Why Other Options Are Wrong:
- Option A: Correct—stratosphere with ozone layer shields UV radiation.
- Option B: Correct—mesosphere exhibits very low pressure and temperatures.
- Option C: Correct—troposphere contains most aerosols, clouds, and weather.
Common Pitfalls:Confusing stratosphere with ionosphere because both are above the troposphere. Only the ionosphere significantly affects HF radio propagation.
Final Answer:Long-distance radio waves are reflected back to Earth by the stratosphere.