UK south west. most dust fell within a period of about 3 days!
Note the new layer on the window
Many cars exhibit this fine buff coloured dust. In sunlight there are reflective bits visible.
Is it volcanic origin?
any way of telling?
If volcanic then the dust is not all above 16000ft. Planes fly through many layers on take off.
Engines suck a lot more air that a windscreen! turbine blades are cooled by through flow air. Turbine blades reach temperatures where glassification can occur.
cooling channels closed by glassified dust will lead to overheat and EVENTUAL failure (see the NASA experience http://www.alpa.org/portals/alpa/volcanicash/03_NASADC8AshDamage.pdf )
From the document:
In the early morning hours of February 28, 2000, the National Aeronautics and Space Administration (NASA) DC-8 Airborne Sciences research airplane inadvertently flew through a diffuse plume of volcanic ash from the Mt. Hekla volcano. There were no indications to the flight crew, but sensitive onboard instruments detected the 35-hr-old ash plume. Upon landing there was no visible damage to the airplane or engine first-stage fan blades; later borescope inspection of the engines revealed clogged
turbine cooling air passages. The engines were removed and overhauled at a cost of $3.2 million. Satellite data analysis of the volcanic ash plume trajectory indicated the ash plume had been transported further north than predicted by atmospheric effects. Analysis of the ash particles collected in cabin air heat exchanger filters showed strong evidence of volcanic ash, most of which may have been ice-coated (and
therefore less damaging to the airplane) at the time of the encounter. Engine operating temperatures at the time of the encounter were sufficiently high to cause melting and fusing of ash on and inside high-pressure turbine blade cooling passages. There was no evidence of engine damage in the engine trending results, but some of the turbine blades had been operating partially uncooled and may have had a
remaining lifetime of as little as 100 hr. There are currently no fully reliable methods available to flight crews to detect the presence of a diffuse, yet potentially damaging volcanic ash cloud.
it's invisible to normal instrumentation
Not seen in normal inspection
Not instantaneously disasterous but severely limit the engines life
If ice covered will not abrade windscreens
There have been few eruptions in european crowded airspace. This may be the first example?
Planes cannot detect dust with radar (it is tuned for water molecules)
Planes cannot therefore steer around a cloud. They would have to use the info from the met models. These have been claimed to be inaccurate!
The met office predicts the path and height.
The met office does not say it is unsafe to fly.
The met office does not fly planes to test the dust cloud.
Who wants 400 deaths on their conscience