Have you noticed lately the sunsets seem to have a purplish hue to them? It’s due to a volcanic eruption that happened months ago on the other side of the globe.
On June 22nd, the Raikoke volcano in Russia’s Kuril islands erupted with a massive explosion, which sent tons of sulfurous gas and fine volcanic aerosols high into the stratosphere. This spectacular eruption was photographed by astronauts aboard the International Space Station. Click here to view these images of the eruption from space.
These aerosols have been suspended in the stratosphere ever since and have circled the globe in the northern hemisphere several times. So how does this make the sunset’s purple in color?
These volcanic aerosols scatter blue light due to Rayleigh scattering. This blue light, when mixed with ordinary sunrise/sunset colors (deep reds), produces a purple hue to the sky.
The best time to look for these amazing colors is about 15 minutes after sunset, which is when the troposphere is in the Earth’s shadow and the stratosphere is still illuminated by the sunlight passing through the lower atmosphere to the west. Since the colors achieve greatest intensity after the sun has set at the surface, volcanic twilights are known as “afterglows.”
Tell your friends and show off your knowledge of the reason for the spectacular purple sunsets. 😉