The mystery of what causes lightning

It seems hard to believe that we still don’t understand what causes lightning during thunderstorms – but that’s a fact.
Famously, Benjamin Franklin was one of the first people to investigate how lightning is triggered. He was correct to conclude that lightning is a natural electrical discharge – those were the early days of harnessing electricity – but it’s not clear that his celebrated kite-and-key experiment in 1752 ever went beyond a mere idea, not least because the kite was depicted, in Franklin’s account, as being flown – impossibly – out of a window.
In some ways we’ve not got much further since Franklin. It’s not yet agreed, for example, how a thundercloud gets charged up in the first place. Somehow the motions of air, cloud droplets, and precipitation (at that altitude, ice particles) conspire to separate positive from negative charge at the scale of individual molecules. It seems that ice particles acquire electrical charge as they collide, rather as rubbing can induce static electricity, and that somehow smaller ice particles tend to become positively charged while larger ones become negatively charged. As the small particles are carried upwards by convection currents, the larger ones sink under gravity, and so their opposite charges get separated, creating an electrical field.
A lightning strike discharges this field. It is basically a gigantic spark jumping between the “live wire” and the “earth” of an electrical circuit, in which the former is the charged cloud and the latter is literally the earth.
While many details of this process aren’t at all clear, one of the biggest mysteries is how the spark gets triggered. Since the electrical fields measured in thunderclouds don’t seem nearly big enough to induce a lightning discharge spontaneously, something is needed to “seed” it. One idea is that they are triggered by cosmic rays streaming into the atmosphere from space. A study has tried to interrogate that notion and finds that, if there’s anything in it, it’s probably not quite in the way we thought.
Out-of-this-world idea
Cosmic rays – mostly protons and electrons – pervade the universe, being produced in awesomely energetic astrophysical processes like supernovae, and they are constantly raining down on Earth. If a cosmic ray collides with an air molecule, this can kick out a spray of fundamental particles and fragments of nuclei. Those in turn interact with other molecules, ionising them and generating a shower of electrons.
In 1997, Russian scientist Alexander Gurevich and his coworkers in Moscow suggested a way in which cosmic rays could be lightning seeds. In the electric field of a thundercloud, these electrons are accelerated, much as particles are in a particle accelerator, creating yet more energetic collisions in a “runaway” process that builds into a lightning strike. This process is expected to produce X-rays and gamma-rays too, and since bursts of these rays have been detected by satellites during thunderstorms, Gurevich’s idea of cosmic-ray-induced lightning seemed plausible.
If the cosmic-ray theory is right, the avalanche of electrons should also generate radio waves, which would be detectable from the ground. Three years ago, Joseph Dwyer of the Florida Institute of Technology began trying to detect such radio signals from thunderstorms, as well as using arrays of particle detectors to look for the showers of particles predicted from cosmic-ray collisions. These and other studies by Dwyer and other groups are still being conducted (literally) at the International Center for Lightning Research and Testing at the US Army base of Camp Blanding in Florida.
Finding avalanches
But meanwhile, Dwyer has teamed up with Leonid Babich and his colleagues at the Russian Federal Nuclear Center in Sarov to delve further into the theory of Gurevich’s idea. (The Russian pre-eminence in this field of the electrical physics of the atmosphere dates from the cold-war Soviet era.) They have asked whether the flux of high-energy cosmic-rays, with their accompanying runaway electron avalanches, is sufficient to boost the conductivity of air and cause a lightning strike.
To do that, the researchers have worked through the equations describing the chances of cosmic-ray collisions, the rate of electron production and the electric fields this induces. The equations are too complicated to be solved by hand, but a computer can crunch through the numbers. And the results don’t look good for Gurevich’s hypothesis: runaway electron avalanches produced by cosmic-ray showers just don’t seem capable of producing electrical breakdown of air and lightning discharge.
However, all is not lost. As well as the particle cascades caused by collisions of high-energy cosmic rays, the atmosphere can also be electrified by the effects of cosmic rays with lower energy, which are more plentiful. When these collide with air molecules, the result is nothing like as catastrophic: they simply ionise the molecules. But a gradual build-up of such ionised particles within a thundercloud could, according to these calculations, eventually produce a strong enough electrical field to permit a lightning discharge.
That possibility has yet to be investigated in detail. But Dwyer and colleagues think that it leaves an avenue still open for cosmic rays to lie at the origin of lightning bolts.

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The Onion spoofs Iran news agency on Obama-Ahmadinejad story

A news agency in Iran has published a report by the satirical news website, The Onion, saying rural white Americans would rather vote for President Mahmoud Ahmadinejad than Barack Obama.

Quoting The Onion word-for-word, Fars states that an opinion poll also found 77% would rather go to a baseball game or have a drink with Mr Ahmadinejad.
A made-up West Virginia resident is quoted as saying: "I like him better."
The report has not yet been published in Farsi on the agency's website.
The Fars news agency, which is affiliated with the powerful Islamic Revolution Guards Corps (IRGC), does not credit The Onion for the report on the survey.
The West Virginia resident is also quoted as saying the Iranian leader "takes national defence seriously, and he'd never let some gay protesters tell him how to run his country like Obama does".
Iran banned alcohol after the Islamic revolution in 1979. Homosexuality is punishable by imprisonment or, in some cases, death.
Iranian media and politicians frequently refer to the US as the "Great Satan".
In 2004, China's state-run Beijing Evening News relayed a report by The Onion which said the US Congress was threatening to move out of Washington unless a new Capitol was built.
And in 2009, two Bangladeshi newspapers apologised after publishing an article taken from The Onion which claimed the Moon landings were faked.

Curiosity Mars rover beams images of ancient streambed

Nasa's Curiosity rover has only been on the surface of Mars seven weeks but it has already turned up evidence of past flowing water on the planet.

The robot has returned pictures of classic conglomerates - rocks that are made up of gravels and sand.
Scientists on the mission team say the size and rounded shape of the pebbles in the rock indicate they had been transported and eroded in water.
Researchers think the rover has found a network of ancient streams.
The rocks, which were described in a media briefing at Nasa's Jet Propulsion Laboratory in California, were likely laid down "several billion years ago". But the actual streams themselves may have persisted on the surface for long periods, said Curiosity science co-investigator Bill Dietrich of the University of California, Berkeley.
"We would anticipate that it could easily be thousands to millions of years," he told reporters.

Satellites at Mars have long captured images of channels on the planet's surface that were cut by some kind of flow, assumed to be liquid water. Curiosity's discovery at its landing site in the equatorial Gale Crater provides the first real ground truth for those observations.
By luck, the rover just happened to roll past a spectacular example of the conglomerate. A large slab, 10-15cm thick, was lifted out of the ground at an angle.
"We've named it Hottah," said rover project scientist John Grotzinger. The name refers to a lake in Canada's Northwest Territories. The team is using names from this region to catalogue objects at Gale.
"To us it just looked like somebody came along the surface of Mars with a jackhammer and lifted up the sidewalk that you might see in downtown LA at a construction site," he joked.
Scientists are now studying the images of the pebbles in the rock. The sizes and shapes will give them clues to the speed and distance of the ancient water flow.
The discovery site lies between the northern rim of the crater and the huge mountain that rises up from its central plain.
Previous orbital imagery of the region had hinted there might have been a water feature there. Curiosity's conglomerates support that hypothesis.

In this view, some of the pebbles have weathered free from the rock

The current interpretation is that the rover is sitting at the head of an alluvial fan of material that washed down through the crater wall and across the plain, cutting many individual streams. Researchers even think they can identify the particular valley at the rim where the water entered the crater, and they have named it Peace Vallis.
There is an eagerness also to study the chemistry of the conglomerates because that will give an indication of the nature of the water - its pH value, for example - and that will provide some clues as to what the environment at the time might have looked like.
At the moment, the rover is heading towards a location dubbed Glenelg. Scientists think this will give them the best access to the rocks of interest.
The US space agency's $2.6bn mission touched down on the Red Planet on 6 August (GMT).
Much of the time since then has been spent commissioning the immensely complex, six-wheeled machine and its suite of 10 instruments.
Curiosity is funded for one Martian year (two Earth years) of study. It will try to determine in that time whether past environments at Gale Crater could ever have supported microbial life.

• (A) Curiosity will trundle around its landing site looking for interesting rock features to study. Its top speed is about 4cm/s
• (B) This mission has 17 cameras. They will identify particular targets, and a laser will zap those rocks to probe their chemistry
• (C) If the signal is significant, Curiosity will swing over instruments on its arm for close-up investigation. These include a microscope
• (D) Samples drilled from rock, or scooped from the soil, can be delivered to two hi-tech analysis labs inside the rover body
• (E) The results are sent to Earth through antennas on the rover deck. Return commands tell the rover where it should drive next

Apple apologises for Maps switch 'frustration'

Apple's chief executive has penned an apology following a barrage of criticism caused by its switch to a new maps system.

Tim Cook acknowledged that users had been frustrated by the move and repeated a pledge to improve the software.
In the meantime he suggested users download an alternative product from one of its rivals.
A link to the letter appears on the firm's home page.
Although the company has issued several apologies over recent months, this one is unusual for its prominence and the fact it was written by Mr Cook himself.
Other examples since July include a letter from the firm's former head of hardware engineering saying that ditching a green ratings scheme had been "a mistake"; a statement acknowledging that changes to its retail stores had been made in error; and emails to iCloud users apologising for an interruption to their email service.
'Frustration' "At Apple, we strive to make world-class products that deliver the best experience possible to our customer," Mr Cook wrote in the latest case.

Rory Cellan-Jones: 'You only need to find a few mistakes and then you've got a big hoo-ha'

"With the launch of our new Maps last week, we fell short on this commitment. We are extremely sorry for the frustration this has caused our customers and we are doing everything we can to make Maps better."

Apple's apology features prominently on its homepage

He noted that more than 100 million mobile device users had upgraded to the new iOS software, replacing a Google-powered maps app with Apple's own software which relies on licensed navigation data.
"While we're improving Maps, you can try alternatives by downloading map apps from the App Store like Bing, MapQuest and Waze, or use Google or Nokia maps by going to their websites and creating an icon on your home screen to their web app," he added.
Bizarre images The Amazing iOS 6 Maps blog has documented the many errors with Apple's new system.
Examples include satellite maps that only show cloud cover, towns located in the wrong place, missing bodies of water, absent roads, incorrectly spelt place names and suggested driving directions that would take users on odd routes.
In addition some of the 3D rendered images look bizarre including a flattened Eiffel Tower, cars that appear to have melted into roads and a road that looks like it has plunged into the US's Hoover Dam.
The product led the New York Times' tech columnist David Pogue, who is often complimentary about Apple's efforts, to write: "Maps is an appalling first release. It may be the most embarrassing, least usable piece of software Apple has ever unleashed."
John Gruber, a tech blogger who closely follows Apple, said his sources had confirmed that Apple had until midway through 2013 to run on its licence deal with Google.
He added that it had decided to act now in order to add turn-by-turn directions to its offering without having to concede extra branding rights or permission for further data collection to the search giant.

Apple has started promoting a maps section in its iOS App Store

'Unusual move' Although owners of older iOS devices have had the option to avoid the system upgrade - forfeiting other improvements - consumers buying the new iPhone 5 have had no option but to use the current Maps app as the device's default option.
One tech analyst said Apple's own users would now prove key to the product's improvement.
"This apology is definitely an unusual move for Apple and it shows that the current service isn't up to its usual standards," said Thomas Husson from Forrester.
"Strategically Apple had to provide a service on its own, not just because it is competing with Google's Android service and lacked turn-by-turn directions, but also because it had to build up its own proprietary data.
"The timing may not have been what it wanted it to be, but it will now be able to crowdsource improvements from the millions of customers who are using the service over the coming months."
Another company watcher suggested that Mr Cook's decision to highlight alternative mapping products was intended to prevent the issue from damaging sales of its new devices.
"This reads like not only an admission of poor quality but also that the product wasn't ready to go to market - Apple took a chance and it didn't pay off," Chris Green, principal technology analyst at Davies Murphy Group Europe, told the BBC.
"This is the worst possible time of year to potentially dampen iPhone 5 sales as the Christmas shopping months will be the most lucrative period in the product's lifecycle.

Users have complained that roads shown on Google's maps (left) are missing from Apple's (right)

"Apple has realised it is not worth damaging sales over something as trivial as maps and they won't lose any revenues by diverting people to products that work."
Apology appeal Despite the number of recent public apologies Apple is proving resistant to issuing one to Samsung.
Lawyers from the companies attended the first day of a hearing at the Court of Appeal in London to discuss applications by both parties to challenge different parts of a recent design rights judgement.
Apple is resisting a demand that it should publish an advert in UK newspapers and on its website acknowledging that the South Korean firm had not infringed the registered design of the iPad.
A judge issued the original ruling after rejecting Apple's lawsuit on the grounds that Samsung's Galaxy Tab computer were "not as cool" as the US firm's.

New 'Sars-like' not easily transmitted says WHO

A new respiratory illness - from the same family as the Sars virus - appears not to spread easily, experts at the World Health Organization (WHO) say.

A Qatari man, 49, with the virus is being treated in London. The first person known to have had it, in Saudi Arabia, died.
The WHO said on Friday that it appeared the new virus "cannot be easily transmitted from person to person."
The Sars virus, which emerged in China in 2002, killed hundreds of people.
Both Sars (severe acute respiratory syndrome) and the new, un-named, virus - as well as the common cold virus - belong to the coronavirus family
But this new virus is different from any coronaviruses previously identified in humans.
Both of the patients known to have had the virus experienced kidney failure.
Zoonotic The WHO said it would continue to monitor the situation but was not recommending any travel restrictions for Saudi Arabia or Qatar.
However it said it was working closely with Saudi authorities in advance of the forthcoming Hajj, the annual Muslim pilgrimage to Mecca.
The WHO also announced diagnostic tests were being developed by scientists around the world as quickly as possible.
The European Centre for Disease Prevention and Control (ECDC), which monitors disease in the European Union, said initial findings suggested the virus may have originated in animals - diseases known as zoonotic.
Writing in the journal Eurosurveillance, they said: "It is quite probably of zoonotic origin and different in behaviour to Sars."