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Possible Volcanic Sunset?

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Author Topic: Possible Volcanic Sunset?  (Read 470 times)
martinastro
Martin Mc Kenna
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« on: October 06, 2009, 04:24:09 pm »

Thanks very much Andy. I asked Les Cowley about these strange sunsets and got the following response...

I'm a decided sceptic about 'volcanic sunsets and twilights' because they have been hyped and there is a tendency to label every colourful wilight as 'volcanic'. However, we have been having a run of them with bright yellow twilight arches and pronounced purple light. They have been spectacular here in Norfolk.

Some information from a colleague in Germany week before last was that idar measurements by the Meteorological Observatory Hohenpeißenberg, southern Germany show that there is indeed a homogeneous layer of mainly sulfuric acid droplets extending upwards from the tropopause up to 20 km high with a maximum density at 13-16 km. This is more or less evenly spread around the northern hemisphere and is 'thought' to be a remnant from the Sarychev eruption. The optical density is enough to produce some twilight effects.

There have been eruptions since Sarychev but this material is evenly spread and the twilight reports are widespread at moderately high altitudes. We were at Fuerteventura three weeks ago (28N) and the twilights there were 'normal' although enhanced ones were reported at higher latitudes.


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