Mie scattering

If particle concentrations are high enough, Mie scattering will overwhelm Rayleigh scattering, resulting in a red sky during the day, rather than the typical blue.

This is known as Mie scattering.

The red color was caused by “mie scattering,” officials said, a phenomenon in which the sun shines on a large number of microscopic smoke particles, which match the wavelength for the color red.

Indonesia’s meteorology agency said the sky had turned red in parts of Sumatra due to the “scattering of sunlight by particles floating in the air, also known as Mie scattering”.

This is a process known as Mie scattering—the scattering of electromagnetic radiation, or light in this case by a sphere.