Which factor causes summer sunsets to sometimes appear muted compared to winter sunsets, even over water?

Answer

High water vapor content causing uniform scattering.

High humidity or water vapor, often present in summer, can cause a uniform scattering effect that muffles the distinct, clear bands of color seen when light passes through drier winter air.

Which factor causes summer sunsets to sometimes appear muted compared to winter sunsets, even over water?

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