Thursday, November 7, 2019

Blazing sunsets, redux

Raikoke Volcano in the Kuril Islands
in the northwest Pacific, taken June 22, 2019.
Credit: NASA.

Those spectacular Hawaiian sunset photos that have been showing up recently on Facebook, Twitter and Instagram are likely the result of volcanic emissions being dumped into the upper atmosphere during the summer.

But volcanic activity hasnʻt stopped. Just in the past week, in addition to ongoing volcanic eruptions, there have been four new ones. The volcanic haze that gets ejected into the atmosphere can color sunrises and sunsets in blazing oranges and purples.

The recent eruptions include these:

Kikai at Japanʻs Satsuma Iwo-jima, which is a small eruption probably not contributing a lot to sunsets. The dust plume was estimated at a kilometer high.

Klyuchevskoy in Russiaʻs Central Kamchatka, which has a dust and steam plume blowing 130 kilometers downwind.

The volcano at Metis Shoal, Tonga, erupted Nov. 1 and created a new island, but it appears to have stopped.

And Shishaldin in the Fox Islands of Alaska is reported still an active eruption, but without reports of a lot of dust and steam.

So those volcanoes that erupted most recently are comparatively small have not created a lot of the color weʻre seeing in the early evening. Most of the impact of recent sunsets comes from Ulawun volcano in Papua New Guinea, which erupted June 26, 2019, and Raikoke in the Kuril Islands, which erupted June 22, 2019.

Ulawun sent up a plume 20 kilometers or more high. Raikoke went 13 to 17 or more kilometers high. At those elevations, the dust and gas got into upper level winds and were transported around the globe.

"The dominant aerosol layer is actually formed by sulfur dioxide gas which is converted to droplets of sulfuric acid in the stratosphere over the course of a week to several months after the eruption. 
Winds in the stratosphere spread the aerosols until they practically cover the globe. Once formed, these aerosols stay in the stratosphere for about two years," said a NASA article.  

If you want to keep track for yourself, hereʻs a website that monitors recent eruptions. It is produced jointly by the Smithsonian Institution Global Volcanism Program and the U.S. Geological Survey.  

For some reason, there has been an upsurge in sunset picture taking. Perhaps itʻs associated with clearer weather. But the underlying causes havenʻt changed much since RaisingIslandsʻ last report on the 2019 sunsets here. 

© Jan TenBruggencate 2019

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