Sunsets often look red or orange because sunlight travels through more atmosphere when the Sun is near the horizon. More of the shorter-wavelength light is scattered out of the direct path, leaving a larger share of the longer wavelengths. The Met Office explains this as the same scattering process behind a blue daytime sky, seen along a different path.
The route through the air gets longer
When the Sun is higher, its light takes a shorter route through the atmosphere toward the ground. Near sunset, that route is more slanted. The longer journey gives air molecules more opportunities to scatter short-wavelength blue and violet light.
The Sun has not suddenly switched to producing orange light. The atmosphere has changed the mixture that arrives along that path. That distinction is the heart of the explanation.
Clouds can take on the warm colors
The Met Office's cloud-color guide explains that cloud droplets scatter visible colors broadly, which helps clouds appear white under ordinary sunlight. Around sunrise and sunset, the light reaching them can already contain a greater proportion of red and yellow wavelengths.
Cloud color is therefore partly a question of illumination. A cloud need not be made of orange material to look orange, just as a white wall can appear warmer under an amber lamp. The wall comparison is an analogy about illumination, not a simulation of cloud physics.
Sunrise follows the same principle
The low angle matters at both ends of the day. There is no separate sunrise mechanism that has to turn blue light into red. Shorter wavelengths are redirected; longer wavelengths make up more of the light continuing along the path.
“Scattered away” also doesn't mean “destroyed.” It means redirected away from the path being described. That is why the direction you are looking matters.
What a colorful sky can tell you
A warm horizon is a prompt to think about the light's journey. It is not, by itself, enough evidence to identify the particles present or promise tomorrow's weather. This article explains the common color mechanism rather than forecasting a spectacular display tonight.
Keep exploring: Why the sky looks blue.
