Sonnenuntergang, 5

Was there any volcano fallout in your part of the wrrld? The one thing I hated about going up to volcanoes was being covered in sand; the really fine stuff would stick to my hair and make my hair like wires.

i never saw any dust on surfaces in the flat, but i assume there was some fallout, because the sky was murky for a week and because my allergies went crazy and my eyes felt as though i'd poured battery acid into them.

Yuck; I hope it's getting much better for you now.

Have you seen this brrd brrain news:
http://news.bbc.co.uk/2/hi/science/nature/8631486.stm

Where is the evidence that *any* of the observations you have reported so far had anything to do with the ash cloud, which was much thinned out when it reached Germany? In the Meteoros forum - Germany's leading discussion group for atmospheric optics - there's a consensus that all effects directly observable are extremely subtle at best. The utter lack of a noticeable sky signature is part of the reason why the government is now under heavy attack for the flight restrictions ...

daniel: what is a sky signature?

regarding my observations, they are simply that: observations. it is possible that these coinciding observations (the dust, the obscured skyline and my out-of-control allergies) are all the result of insane levels of pollen and are absolutely unrelated to the icelandic volcano. or all these observations might be the result of engrams.

i am not a professional vulcanologist, but having lived with asthma and very severe allergies all of my adult life (likely the result of living several years in volcanic ash from another eruption when a child), i know from experience that my allergies and asthma are never this out-of-control when i've relocated to a new home, as i've done only a few months ago. numerous epidemiological and immunological studies support my observations. so, based on that alone, it is extremely unlikely that my allergic response is due to pollen, even if there is a tremendous amount of pollen in the air.

further, it is obvious that there is some form of fine dust in the air that has obscured the nearby hills and the sun -- whatever these fine airborne particles are, they mysteriously appeared suddenly on saturday and only are now clearing out. since i daily photograph the hills and the city from the windows of my flat, these differences are not only easy to see, but i've also been documenting them by accident.

all of these observations are correlated to the proposed appearance of the icelandic volcanic ash cloud over frankfurt -- an ash cloud that closed the airport.

are all these observations coincidence? um, sure. if you insist.

Well, have a look at reports from the Netherlands and Germany by two very experienced sky observers specialized in atmospheric optics who see no significant volcano-related effects in Central Europe at all.

While LIDAR as well as airborne in-situ data showed - according to a flurry of press releases since Monday - that the ash concentration is highly variable in space and time, there was no report to the effect that it ever reached values high enough for significant obscurations and/or twilight effects beyond Iceland and the British Isles.

the most parsimonious explanation for all the observations i've been making is that the volcanic ash was doing it. can you provide another explanation for everything i've been photographing and experiencing?

(incidentally, the sky is filled with ugly contrails once more as the air traffic explodes back to normalcy, the sky is a clear cloudless blue, the horizon is sharply visible and the sunsets aren't as red as they were these past five or so days. oh, and the allergies/asthma is gone, too).

@Daniel: You're an idiot, and I can say that because I have been involved for many years with research on volcanic ash and aviation. Despite your ridiculous claims, this photograph and grrl's mention of her allergic reactions tells me that it is very likely that most of this effect photographed is due to the volcanic particles. Dust storms in North Africa can also cause this effect (some industries can as well, but not since regulations in the past 30 years), but currently there are no such dust storms. The photograph is also consistent with the satellite data showing where the volcanic ash is located. The clouds were a nuisance throughout the event because they hide the extent of the plume. We finally have a statement from one engine manufacturer detailing what they believe to be an upper safe limit of exposure for their engines, and the stated values are far below what is being observed throughout Europe as confirmed by various instruments in the satellite set referred to as the 'A-Train'. If there are any LIDAR stations out there operating at multiple frequencies and preferably also looking at depolarization we may get independent station data on local conditions, but we don't even need the data from those stations to know what's going on; the satellite data in this instance is sufficient.

@ Grrlscientist & MadScientist:

I can't say anything about the German photographs reported in this post, but I can say that much of the haze we are seeing here in the Netherlands the past week, is normal cirrus. My blog post linked by Daniel gives you picture evidence (halo caused by ice particles, = normal cirrus) and I photographed another nice halo a few days later which can be seen here: http://i19.photobucket.com/albums/b176/marcoaliaslama/halo20APR2010.jpg
These halo's prove it is high altitude clouds made up of ice particles (= cirrus): not dust particles. With the latter, you get different optical characteristics.

Cirrus is quite normal for April in NW Europe, especially under the weather conditions of the past two weeks. And due to the lack of rain (no rain here for two weeks, see my data: http://i19.photobucket.com/albums/b176/marcoaliaslama/weer/regen_apr_20…), the amount of pollen in the atmosphere is currently very high, explaining the allergic reactions. So I don't think Daniel is an idiot with his comments, Madscientist.

@Marco: How can you say normal cirrus? The volcanic plume does not necessarily look like a cloud (unless you're very close to the source). Have you measured the scattering of light through the atmosphere and estimated the amount of particles and their size distribution? Did you use other instruments to determine if what you see are non-volcanic aerosols? One manufacturer has (finally) released information on what they consider to be an upper limit to the acceptable volcanic ash loading and the number is so small that as far as the human eye is concerned it would appear no different than scattering by a typical marine aerosol. This is not a situation which is easy to judge by sight; if it were then aircraft would simply fly and pilots will be left to make decisions. The fact that in the past there have been about 200 reported volcanic ash encounters and none of those pilots could tell that they were headed for ash is a pretty good indication that sight is not helpful. One of the reasons people are trying to develop instrumentation is that in many of these cases the pilots reported seeing only a haze (description of the haze varies widely) or seeing what appeared to be normal ice/water clouds. Unless you're near the volcano, the plume looks nothing like what you've been seeing on TV. Even after many hundreds of hours right next to volcanoes I don't even trust myself to reliably distinguish orographic clouds from a small puff from the volcano, I have to rely on my instruments.

Your understanding of halos is not correct; it is slightly less incorrect if you limit yourself to ice crystals or water droplets. Have you done calculations to determine what to expect when volcanic ash scatters light? Daniel is very clearly making claims which are wrong and cannot be substantiated. If people listen to such nonsense, then decisions will be made contrary to what we know from science and contrary to what engineers have established by testing in laboratories. In the one site he links to perhaps the author means well, but he is absolutely wrong with his conclusions; there is no evidence to support his conclusions that there is no sign of any effect from volcanic aerosols; the author clearly has no idea what to look for. Now even if we established with instruments that it was clear in that specific area, there is still the challenge of determining how clear the path is between any two airports, and also how quickly changing conditions can make the flight path hazardous. Do you have any idea how fast the winds move at the cruising altitude of these aircraft? All of the information so far, including the results of various analyses being done by many colleagues on a variety of satellite instrument data all indicate that closing down the airports was the correct decision. Disruptions like these are rare; in fact European air transport has never been affected like this before, but it would be foolish to fly just because you believe it would be safe, contrary to what the evidence indicates. The aircraft operators should stop crying and get back to business. This disruption is hardly any different from what some airports experience when there are large storms in the region; just because that doesn't regularly happen in Europe doesn't mean it is fine to ignore nature and do things as if conditions were normal.