The first is that by taking advantage of the jetstream, aircraft are flying within an airspace that is also preferentially occupied by volcanic eruption clouds and particles.
Registered under the the Historic Vehicle class for free road tax. Comes with an older V5 registration document, the latest DVLA V5C registration document, is registered under the 'Historical Vehicle' class for free road tax & is MOT exempt. We are informed that recent work includes a top end & cooling system rebuild, plus a replacement differential & rear axle, with all work being carried out to a very high standard. I also have a modern Ducati Multi Strada 1000DS that can be traded in if anyone is interested. Model plume trajectories compare well with the observed plume trajectory of the Sept 30/Oct 1, 1994, eruption of Kliuchevskoi Volcano, Kamchatka, Russia, for which measured maximum windspeed was 30–40 m/s at about 12 km.Tephra fall patterns for some prehistoric eruptions of Avachinsky Volcano, Kamchatka, and Inyo Craters, CA, USA, are anomalously elongated and inconsistent with simple models of tephra dispersal in a constant windfield.The polar jets or jetstreams are regions of high [generally eastbound] winds that span the globe from 30 to 60° in latitude, centered at an altitude of about 10 km.They can be hundreds of kilometers wide, but as little as 1 km in thickness. Modern transcontinental and transoceanic air routes are configured to take advantage of the jetstream. Matching engine and frame numbers, original paint and chrome, unmolested.