Monday, September 16, 2019

Those blazing new internet sunsets? Thank a couple of summer volcanic eruptions.

Great sunsets are the new kitties on social media.

Lots of folks are posting their photographs of 
spectacular glowing orange and purple sunsets. Whereʻd they come from? 

Once again, this pulse of superb sunsets is thanks to atmospheric pollution from a volcano.

(Since youʻll find sunset shots elsewhere, hereʻs a shot of whatʻs causing them. This is the plume from Kuril Islands volcano Raikoke, taken from the International Space Station. Credit: NASA.)

This time, it is the Russian volcano, Raikoke, which erupted in June this year. The volcano dumped vast amounts of sulfur gas into the upper atmosphere, giving sunsets a new reddish-purple tinge.

High altitude balloon measurements just found sulfur density 20 times normal in the stratosphere. The story was reported in last weekʻs issue of the journal Science

There were some great sunsets in 2008, that time due to the ash-filled eruption of the Alaskan volcano Kasatochi. It exploded in August of that year.  

And there were years of great sunsets in the 1990s from the Philippine volcano Pinatubo, which erupted in June 1991.

(In the NASA images from space at left, the upper shot is before Pinatubo. In the lower image, the layers of aerosols from 1991ʻs eruption of Pinatubo are visible in the atmosphere.)

The latest bit of atmospheric pyrotechnics is thanks to Raikoke or Raykoke, a Russian volcano that dominates an island in the Kuril chain of the Northwest Pacific. The June 22 eruption ejected a plume of sulfur dioxide and particulate matter 50,000 feet into the atmosphere.

The Raikoke event may be helped a little by another eruption in the first week of August, this one from the volcano Ulawun in Papua New Guinea. Its plume is believed to have reached 63,000 feet.

But while those are impressive events, the volume is not believed to be sufficient to alter climate. Pinatubo was identified responsible for a two-year period of global cooling that temporarily halted the planetʻs pattern of warming.

Pinatubo lifted 15 million tons of sulfur dioxide into the atmosphere, where it formed a layer of sulfuric acid droplets that both blocked sunlight and made great sunsets. 

© Jan TenBruggencate 2019

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