Skies in Australia turn blood-red: Here’s what happened

Dramatic scenes of blood-red skies have recently been seen in Western Australia. Residents can closely explore the science of atmospheric light as sunlight is made of all the colors of the rainbow, which interact with gas molecules and dust in the air. The sky usually looks blue because shorter light wavelengths scatter easily when the sun is overhead.

At dawn or dusk, sunlight travels through a much thicker layer of the atmosphere, filtering out shorter blue wavelengths and leaving only the longer reds. Meanwhile, high levels of dust, smoke, or pollution make these red hues much more vivid. In Western Australia, powerful winds from Cyclone Narelle off the coast kicked up massive amounts of desert sand, providing the fuel for these dramatic, blood-red skies.

Larger particles like dust trigger a process called Mie scattering, which specifically intensifies red and orange tones to create a blood-red appearance. The phrase “red sky in the morning" has a scientific basis; it often indicates the sun is reflecting off incoming clouds from the west. Red morning skies can be a natural signal that rain or a storm is approaching, as sunlight hits microscopic water particles at low angles.