The sky looks pink mainly because of how sunlight is scattered in the atmosphere, especially around sunrise and sunset when light takes a longer path through the air. Shorter blue and violet wavelengths are scattered out of your direct line of sight, leaving more of the longer red, orange, and pink wavelengths to reach your eyes.

The basic science

  • Sunlight is made of many colors, each with a different wavelength.
  • The atmosphere scatters short wavelengths (blue, violet) more efficiently than long ones (red, orange). This process is called Rayleigh scattering.
  • When the sun is low on the horizon, its light crosses a thicker slice of the atmosphere, so even more blue light is scattered away, letting reds and pinks dominate.

Why pink instead of red

  • On some days, sunsets are deep red or orange; on others they are softer pink. The exact color mix depends on the balance between scattered blue light and direct red/orange light.
  • Thin or high clouds can reflect and mix this reddish light with remaining white light, creating pastel pink skies and pink clouds.

Extra factors that change the pink

Several atmospheric conditions tweak how intense or soft the pink looks:

  • Humidity : Water vapor can coat tiny particles, making them block or diffuse light more, which can soften bright reds into gentler pinks.
  • Aerosols and dust : Clean air tends to give more vivid reds and oranges; pollution and dust often mute the colors and can make sunsets look more washed-out pink instead of fiery red.
  • Season and angle of the sun : In some seasons, the sun’s path gives longer sunsets and more time for colors to develop, sometimes producing extended pink skies, especially in colder, clearer air.

Daytime pink skies

While pink skies are strongest at sunrise and sunset, they can occasionally appear at other times:

  • After storms or volcanic eruptions, unusual particles in the upper atmosphere can shift scattering and create striking pink or purple skies.
  • High, thin clouds catching sunlight at just the right angle can glow pink even when the rest of the sky still looks blue.

In forum-style discussions, people often describe it simply as “the sun’s light going through more atmosphere so the blue is stripped away and the leftover warm colors paint the sky pink.”

TL;DR : The sky turns pink when sunlight passes through a thick layer of atmosphere, scattering away blues and letting reds and oranges dominate, often softened and reflected by clouds and local air conditions.

Information gathered from public forums or data available on the internet and portrayed here.