A phonecall in the dead of night was the first inkling the people living on the Thorvaldseyri farm had that Iceland’s glacier-covered Eyjafjallajokull volcano was about to erupt.

Hanna Lara Andrews, a half-English, half-Icelandic farmer who lives at the foot of the mountain which exploded on Wednesday morning with ferocious power, picked up the phone at 2am to be told by a civil protection official that she had only 20 minutes to evacuate her family, including her one-year-old son.

The warning was clear: if they stayed on their dairy farm they risked being washed away by torrents of meltwater unleashed by the release of energy that had just begun inside the volcano, no more than four miles above them.

It would be the volcano’s first major eruption since 1821, since when it has lain dormant and anonymous to most of the world. Yesterday it made headlines when it transformed swaths of western Europe and Scandinavia into an unprecedented no-fly zone.

“I had a bag ready because of the recent earthquakes in the area and grabbed a few things we might need for a couple of days and we went as quickly as possible,” Andrews said from a safe house yesterday. “It is a huge shock to us all and it doesn’t seem real at all.”

Her family, including her in-laws, drove a few miles away to a farmhouse designated for evacuation in the event of such an eruption. There they waited in trepidation for the possible destruction to begin. Their herd of 60 dairy cows and all their possessions were still at the farm – the closest property to a volcano that they had thought was dormant. They were among 700 people evacuated from the area by the Icelandic civil defence authority. Many had to stay in emergency Red Cross shelters.

The floods arrived early the next morning. Andrews saw them coming down the mountain. Water melted by the red hot explosive eruptions bursting through the 200m-thick glacier poured off in torrents, washing away roads and sweeping into homes, she said.

“By morning we could see through breaks in the cloud a huge evaporation cloud, like a mushroom. It must have been 20,000ft [6,100 metres] high. It looked enormous, far bigger than we have ever seen before.”

It was such an astonishing sight, her father-in-law, Olafur Eggertson, took a picture of the eruption dwarfing the family’s red-roofed farm.

Such was its force that three large holes visible on the glacier turned into a continuous rift running for about a mile and a half through the ice, said Rognvaldur Olafsson, who led the rescue effort for the civil defence authority.

Mercifully, the wind, blowing east, carried the plume of ash away from Reyjkavik, the capital, but across farmland, where it turned day into night as it fell and blotted out the sun. This led to speculation, later played down by experts, that the eruption may have the potential to slow global warming.

One local farmer told Icelandic television that he woke yesterday morning to find a layer of ash covering everything. Residents of Kirkjubaerklaustur, about 60 miles east of the eruption, said yesterday that ash was falling thick and dark, making it difficult to see more than a few yards.

“The ash is causing huge disruption to the east of the glacier,” Urður Gunnarsdóttir, a press spokeswoman for the foreign ministry, said at lunchtime yesterday. “You can’t see anywhere and you can’t drive because it is just black, like night.”

Erlundur Bjornsson, a sheep farmer 95km (59 miles) east of the volcano, told the Guardian that ash had fallen heavily and it had been “almost totally dark”.

“The plume came over my farm a couple of hours ago, but the wind direction has changed slightly and it is very fine here, a grey dust that gets in your eyes,” he said. “It covers everything and there is a smell of sulphur in the air.”

In the early hours of yesterday, 24 hours after the eruption began and with the volcanic activity still intensifying, according to Icelandic volcanologists, the plume had risen seven miles into the sky and had blown across the Norwegian Sea to Scandinavia, and south east across the Shetland Isles, as far as the north coast of Scotland. The Met Office in Exeter produced diagrams showing the plume doubling again and again in size as it stretched to cover an area close to the size of Western Europe.

Shetland residents said the sulphuric smell of rotten eggs was strong by early yesterday morning.

“I noticed a smell in the house and wondered what it was,” said Joanne Jamieson, from Sandwick on the southern tip of Mainland, the biggest island in Shetland. “It was coming from the outside, so I opened the door. It was very strong, and I initially thought it was rotting seaweed. I looked down to the beach and actually looked up to see if the sky was falling in.”

Jane Matthews, her neighbour, said: “It smelt strongly like rotten eggs, but I didn’t put two and two together realising it was coming from Iceland,” Initially, I thought maybe it’s something to do with my young daughter, or the animals in the field.”

Air traffic controllers in Aberdeen had seen the plume coming. By noon on Wednesday they had predicted that local airspace could be closed for a few hours, but by evening it was clear the situation was more serious than that.

Aberdeen airport’s duty manager was alerted by Nats, the air navigation service, that its local north-east airspace would be closed. At 1am on Thursday, the closure order was confirmed, affecting more than 100 commercial flights during the day. By 3am, the whole of Scotland became a no- fly zone. Before dawn the Scottish government’s civil emergency resilience unit was activated.

By 9.30am air traffic control charts showed that planes were only taking off and landing across southern England. Anywhere north of that, the skies were empty. At 11am Gatwick’s busy tarmac apron was at a standstill as airport managers prepared for a national shutdown of British airspace, which began at noon.

Russell Craig, head of communications at Manchester airport, where 45,000 passengers were affected and hundreds of flights were cancelled, said: “It is difficult for passengers to understand because the planes are there and the sky is blue, but it would be dangerous to fly a plane in these conditions.”

Small aircraft were able to take off, said Craig, and the airport remained open in case a long-haul plane needed to execute an emergency landing.

By 2.30pm the vast cloud had reached across England, and fears that its fine particles could cause passenger jets to crash caused an unprecedented shutdown of all of Britain’s airports. No flights were to be allowed in or out until 7am this morning at the earliest. And a video http://www.youtube.com/watch?v=dS9FgSVKeN4

Þjórsá is Iceland’s longest river at 230 kilometers. It is in the southern region of the island.

The river Þjórsá with the glaciers Tindfjallajökull and Eyjafjallajökull

Þjórsá has its source on the glacier Hofsjökull. It flows out through narrow gorges in the highlands of Iceland. Then it passes by the historical farm of Stöng. Further downstream, another river, the Tungnaá, flows into it (see also Háifoss), before it enters the lowlands.

In the middle of the now rather wide river, there is a big island called Árnes, where in the past, was situated a Þing place. The administrative unit of Árnessýsla was named after it

In physics, radiation describes any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body. Non-physicists often associate the word with ionizing radiation (e.g., as occurring in nuclear weapons, nuclear reactors, and radioactive substances), but it can also refer to electromagnetic radiation (i.e., radio waves, infrared light, visible light, ultraviolet light, and X-rays) which can also be ionizing radiation, to acoustic radiation, or to other more obscure processes. What makes it radiation is that the energy radiates (i.e., it travels outward in straight lines in all directions) from the source. This geometry naturally leads to a system of measurements and physical units that are equally applicable to all types of radiation. Some radiations can be hazardous. og hér er Dæmi að ef þú setur gamla ljósaperu í örbylgjuofn http://www.youtube.com/watch?v=oHg5SJYRHA0 oghttp://www.youtube.com/watch?v=mARTSw8gp7c

Space debris, also known as orbital debris, space junk and space waste, are objects in orbit around Earth created by humans that no longer serve any useful purpose. They consist of everything from entire spent rocket stages and defunct satellites, to explosion fragments, paint flakes, slag from solid rocket motors, coolant released by RORSAT nuclear powered satellites, deliberate insertion of small needles, and many other objects. As orbits often overlap, debris is a potential collision risk for spacecraft.

The vast majority of the estimated tens of millions of pieces of space debris are small particles, like paint flakes and solid rocket fuel slag. Contact with these particles causes erosive damage, similar to sandblasting. The majority of the damage can be mitigated through the use of a technique originally developed to protect spacecraft from micrometeorites, by adding a thin layer of metal foil outside of the main spacecraft body. Impacts take place at such high velocities that the debris is vaporized when it collides with the foil, and the resulting plasma spreads out quickly enough that it does not cause serious damage to the inner wall. However, certain portions of many satellites cannot be protected in this fashion, the solar panels and windows for instance, and are subject to constant wear by debris and micrometeorites.

Larger debris, 1 kilogram (2.2 lb) or heavier, presents an entirely different problem. A collision with an object of this size at orbital velocities will typically destroy the spacecraft. The only protection is to move the spacecraft out of the path of any known objects. The ability to find space debris in low earth orbit (LEO) falls off quickly below 10 centimetres (3.9 in) in size, while for higher orbits, like geostationary orbit (GEO), the limit is larger than 1 metre (3 ft 3 in). This leads to wide uncertainties in the estimated quantities of debris, and the predicted path of their orbits. Over the span of the last decade, the estimated number of objects in LEO in this size range has more than doubled, from about 8,500 in the late 1990s, to 19,000 in a 2009 measurement.

If a collision with larger debris does occur, many of the resulting fragments from the damaged spacecraft will also be in the 1 kilogram (2.2 lb) mass range, and these objects become an additional collision risk. As the chance of collision is a function of the number of objects in space, there is a critical density where the creation of new debris is faster than the various natural forces that remove these objects from orbit. Beyond this point a runaway chain reaction can occur that quickly reduces all objects in orbit to debris in a period of years or months. This worrying possibility is known as the “Kessler Syndrome”, and there is debate as to whether or not we have already reached this critical density in certain orbital bands. smella hérna til þess að vita meira http://www.youtube.com/watch?v=6Fy7psIuJjc

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