Color of the Sun at Sunrise vs Noon vs Sunset (Physics Behind It)

The Sun’s Apparent Color

The Sun emits light across the visible spectrum which when combined appears white. However, the color we perceive depends not just on the Sun itself but on how its light interacts with Earth’s atmosphere. This is why the Sun can appear red, orange, yellow or white depending on its position in the sky.

Atmospheric Scattering

The main reason the Sun changes color during the day is Rayleigh scattering. This is a phenomenon where shorter wavelengths of light (blue and violet) are scattered more than longer wavelengths (red, orange, yellow) by the molecules and tiny particles in the atmosphere. This scattering affects the spectrum of sunlight that reaches our eyes at different times.

Sunrise (Early Morning)

At sunrise, the Sun is near the horizon so sunlight has to travel through a thicker layer of the atmosphere. The shorter blue and violet wavelengths are scattered out leaving mostly red and orange wavelengths. This is why the Sun often looks reddish or orange in the morning. Atmospheric conditions like dust, pollution and humidity can intensify this effect.

Noon (Midday)

At noon, the Sun is almost directly overhead so its light passes through less atmosphere. Less scattering of blue light occurs so the Sun appears much brighter and whiter. The sky around it looks blue due to the scattered blue wavelengths reaching our eyes from all directions. This is why midday sunlight is perceived as the most intense and “pure” white.

Sunset (Evening)

Sunset is very similar to sunrise in terms of physics. The Sun again passes through a longer path of the atmosphere causing most of the blue light to scatter out and leaving red, orange and pink hues. Differences in local conditions like humidity or air pollution can make sunsets even more vivid than sunrises .

Influence of Dust and Pollution

Particles like dust, smoke and water droplets amplify the scattering effect. This is why regions with more pollution often have more intense red or orange sunrises and sunsets. Larger particles can also cause Mie scattering, which affects all wavelengths more equally and can soften the colors or create hazy skies.

Summary
1. Sunrise & Sunset: Longer atmospheric path → more scattering → red/orange hues.
2. Noon: Shorter atmospheric path → less scattering → bright white Sun.
3. The colors of the Sun and sky are a direct consequence of how sunlight interacts with Earth’s atmosphere.