- If violet light is scattered even more than blue light, why does the sky look blue and not violet?
- This is an excellent observation. While the scattering law does predict violet light is scattered most strongly, two main factors explain the blue sky. First, sunlight contains less violet intensity to begin with compared to blue. Second, and more importantly, the human eye is less sensitive to violet light than to blue and green. The combined signal from the scattered light across the spectrum, weighted by our eye's sensitivity, peaks in the blue region.
- Why does the sky look white or hazy near the horizon on a cloudy day?
- The model focuses on Rayleigh scattering by molecules, which dominates on clear days. Hazy or white skies indicate the presence of larger particles like water droplets, dust, or pollution aerosols. These particles scatter all wavelengths of light more equally (a process called Mie scattering), washing out the strong blue color and creating a whitish appearance. This simulator simplifies by not including this type of scattering.
- Does the simulator show why the sun itself looks red at sunset?
- Yes, indirectly. When the sun is low, its light travels a much longer path through the atmosphere to reach your eyes. Along this long path, most of the shorter blue wavelengths are scattered away in all directions. The light that reaches you directly from the sun is therefore depleted in blue, leaving predominantly the longer red and orange wavelengths, making the sun appear red. The sky gradient in the simulator illustrates this increased scattering path.
- Is the 'inverse fourth power' (λ⁻⁴) relationship just a mathematical model, or does it have a physical cause?
- It has a direct physical origin derived from classical electromagnetism. For particles much smaller than the wavelength, the oscillating electric field of the light induces a dipole moment in the molecule. The radiated (scattered) power from an oscillating dipole depends on the frequency to the fourth power (or inversely on λ⁴). This is not an arbitrary fit but a theoretical prediction for ideal, small scatterers.