Which best explains why the sun appears reddish at sunrise? a) blue wavelengths of light have already been scattered before reaching the observer. b) red wavelengths of light have already been scattered before reaching the observer. c) the sun emits light rays comprised of higher wavelengths at sunrise. d) the sun emits light rays comprised of lower wavelengths at sunrise.

The answer is A. This is because sunlight is composed of various wavelengths in the electromagnetic spectrum. In the visible light spectrum, red light has a higher frequency (lower wavelength) than blue light that has a lower frequency (higher wavelength). Therefore red light has higher energy than blue light hence able to penetrate more into the atmosphere before scattering, compared to blue light. At sunrise and sunset, due to the relative angle  of the sun to the observer, the sun rays have to penetrate a thicker layer to the atmosphere before reaching the observer