Pictures: Volcano Supercharges Sunsets Far and Wide

Volcanic Sunset
Photograph by Patricio Rodriguez, Reuters
A cloud of ash from Chile's Puyehue volcano (map), which began erupting on June 4, creates a golden-hued sunset near the mountain resort of San Martín de Los Andes in Argentina on June 12. (Pictures: Chile Volcano Plume Explodes With Lightning.)
The corrosive and obscuring volcanic ash has grounded airplanes all across South America and even in Australia, but the tiny dust and glass particles are also responsible for an optical effect that has lead to spectacular sunsets and sunrises filled with bright gold, fiery orange, and blood red hues around the globe.
"The wavelength of light coming from the sun is being diffracted differently, and that's what causes the visual effect that we see," explained Jay Miller, a volcanologist at Texas A&M University.
The transformed light can range across the color spectrum, but it's usually a dark color, because less sunlight penetrates the atmosphere as a result of the ash cover.
"The two most important things [with respect to] to the variation in hues that we see are how much ash and how high in the atmosphere it gets," Miller said. "A bunch of ash hugging the ground would just make it dark."
—Ker Than
Published June 17, 2011
Under a Blood Red Sky
Photograph by Carlos Gutierrez, Reuters
A plume of ash rises high into the atmosphere and tints the sky blood red above Chile's Puyehue volcano in this June 5 photograph.
The Chilean volcanic eruption happened to occur during the longest total lunar eclipse in more than a decade, which occurred on June 15. (See pictures of the June 15 lunar eclipse.)
Many sky-watchers reported that the eclipsed moon appeared rusty orange or blood red. This type of color transformation isn't uncommon during eclipses, because dust and gas in the Earth's atmosphere can filter blue wavelengths from the sun's rays, but ash particles from the Chilean eruptions could have helped enhance the effect for this particular eclipse. (Find out how the lunar eclipse worked.)
"I would assume there was some impact," Miller said. "Anytime there's a large amount of ash in the atmosphere, we have reports of this type of phenomenon."
Published June 17, 2011
Moonlike Sun
Photograph by Cezaro de Luca, EPA
Wisps of volcanic ash float across the setting sun, which appears to have been leached of all its color in this photo taken from Buenos Aires, Argentina, on June 13. Ash from the Puyehue eruption continues to plague the capital city of Argentina, grounding airplanes and shutting down airports.
Dormant for decades, the volcano erupted again on June 4 and lofted an ash cloud more than six miles (ten kilometers) into the atmosphere.
That might seem impressive, but eruptions have been known to launch ash more than 19 miles (30 kilometers) into the air, Miller said.
(Related pictures: "Chile Volcano Erupts With Ash and Lightning [2008].")
Published June 17, 2011
Clouds, and a Silver Lining
Photograph by Patricio Rodrigue, Reuters
Ash clouds mingle with normal water clouds at sunset near the mountain resort of San Martín de Los Andes in Argentina's Patagonia region on June 5. (See Patagonia pictures.)
Besides grounding airplanes and changing the colors of sunsets, volcanic ash clouds can generate impressive lightning displays as static electricity builds up from ash particles rubbing together, Miller said. (Iceland Volcano Pictures: Lightning Adds Flash to Ash.)
Ash particles can also serve as the seeds for rainstorms, he added. "You have to get the water vapor to precipitate around some thing," in this case specks of dust and glass. (See "Volcanic Lightning Sparked by 'Dirty Thunderstorms,' Study Finds.")
Published June 17, 2011
Silver and Gold
Photograph by Patricio Rodriguez, Reuters
Golden sunlight illuminates ash clouds at sunset above mountains in Argentina on June 12.
The microscopic dust and glass particles in volcanic ash can act like the smog particles that hover above cities and change the color of sunrises and sunsets.
"Smog is a different type of particulate than ash that comes out of a volcano, but it's the same net effect," Texas A&M's Miller explained.
"The atmosphere is like a prism, and when there's particulate matter in it, light passing through [the atmosphere] gets diffracted and you see different colors in the spectrum," he said.
Published June 17, 2011
Volcano to Volcano
Photograph by David Frampton, AP
The air above New Zealand's Mount Taranaki volcano glows orange and red on June 12 as a result of light-bending ash particles from the volcanic eruption in southern Chile.
Many airlines grounded flights to and from southern Australia and New Zealand on June 13 after the ash cloud had expanded.
The altered sunsets and sunrises following a volcanic eruption can persist for several months, Miller said.
For example, "the 1783 eruption of Laki in Iceland lasted for several months, but people were reporting different colorations in the sunset and sunrises in Europe for many months after that," he said.
Published June 17, 2011