Why are some volcanic plumes colorful? Geologists explain the mystery

Why are some volcanic plumes colorful? Geologists explain the mystery
This photo shows the sun shining behind a volcanic gas plume, giving off an orange color (Image: USGS)
The gas plume is against a very dark cloud background, while the sun is behind the photographer, making the plume appear blue (Image: USGS)
The gas plume is against a very dark cloud background, while the sun is behind the photographer, making the plume appear blue (Image: USGS)

KILAUEA VOLCANO, BIG ISLAND (HawaiiNewsNow) - The Kilauea volcano is creating more mesmerizing sights as it continues to erupt in lower Puna.

The latest to come to light: Colorful plumes.

In some instances, the plume generated by lava spewing has been giving off a faint color – sometimes appearing slightly off-white, light blue, yellow, brown or orange.

The answer to this mystery? It's created by the scattering of light within the plumes.

The USGS explains that high temperature volcanic gases consist of mostly water vapor, and that most gas plumes are often a white color due to sunlight being scattered on water droplets condensing within the plume while it cools.

In addition to water vapor, some plumes also contain large amounts of sulfur dioxide, which react with atmospheric gases to form sulfate aerosols – tiny solid particles -- when emitted.

These are much smaller particles, which in turn, give off different colors than the water droplets because the scattering process is slightly different.

The tiny particles will scatter the short wavelengths of blue light more efficiently than the longer wavelengths of red light, the USGS says.

If a white light enters the plume – like by pointing a flashlight at it – then the returning light might emit a blue tint because of the enhanced scattering of blue wavelengths.

The plumes that show off an orange color are also caused by the same effect, just in different illumination geometry. For example, when the sun is behind a plume with a large amount of sulfate aerosols, the light will be scattered differently.

Though it creates an interesting sight, USGS officials also warn that sulfur dioxide is highly toxic and they urge people to stay away.

This is the latest phenomena arising from the Kilauea eruptions that began on May 3.

In addition to high levels of sulfur dioxide gas being detected near the fissures, lava flows from several fissures have been spewing what's known as Pele's hair, or fine strands of volcanic gas. And, blue flames have also been burning through cracks on streets in Leilani Estates. Scientists say it's a blue burning flame of methane gas, which is produced as a byproduct of burning vegetation.

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