Give reasons for the following : The sky appears dark to the passengers flying at very high altitudes.
Generated by claude-sonnet-4-6 · 2026-06-15 06:54 · grounding rag
Model Answer
At very high altitudes, the atmosphere is very thin and there are very few particles present to scatter sunlight. Since scattering of light is not prominent at such heights, the blue colour (which is scattered by atmospheric particles near the earth's surface) does not reach the passengers' eyes. Hence, the sky appears dark to them.
Source: Chapter 10, Section 10.6.2 – Why is the colour of the clear Sky Blue?
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Explanation
- The key concept is scattering of light: fine atmospheric particles near the earth's surface scatter shorter (blue) wavelengths, making the sky appear blue.
- At very high altitudes, the atmosphere is very thin, so scattering is negligible → sky looks dark.
- The textbook directly states: "The sky appears dark to passengers flying at very high altitudes, as scattering is not prominent at such heights." Always use this line as the concluding statement.
- Examiners look for: mention of scattering, thin atmosphere/fewer particles, and the result (sky appears dark). Don't write about blue colour in detail — just connect its absence to why the sky looks dark.