Scientists discover how to make on-demand lightning

Wikipedia Back in the days of ancient Greece or Rome, if someone could magically generate lightning-on-demand they’d probably be hailed as a god. Until not too many years ago most people believed that lightning and the roaring thunder that follows were some sort of warning or punishment from the heavens.

Well now scientists in New Mexico have put an end to those theories – or at least they nearly have. By firing lasers into a thundercloud they just about managed to generate a bolt of lightning. They didn’t actually manage it because their techniques aren’t yet well enough developed, but they say they should be ready before too long.

It sounds pretty cool doesn’t it, lightning whenever and wherever you want it (although obviously it only works when you’ve got a thundercloud). So how did they do it? It sounds almost like science fiction: they shot laser beams up into thunderclouds, which caused a line of gas in the cloud to become ionized – that means it was given a charge.

Wikipedia Because lightning is essentially just a huge stream of charged particles, the line of particles that the laser created acted much like a lightning rod, and it directed the flash of lightning downward. It didn’t hit the ground in this experiment because the technique used was not powerful enough, but before long scientists should have mastered the technology.

Wikipedia It’s all very well being able to generate lightning, but as with so many experiments like this you just have to wonder, well, why? Actually, it could have some good uses. By knowing exactly when and where lightning is going to strike, scientists can do their research into this deadly killer a lot more easily. It’s also going to be useful for testing how lightning-resistant new planes and power lines are.

We’ve already discovered how to create rain (well at least sort-of), and now we can make lightning. It’ll be interesting to see where weather research takes us next in the decades ahead. I bet those scientists wish they lived in Ancient Rome – think of all the special treatment they’d get now as gods!

National Geographic has an excellent interactive page showing how lightning works.

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Why do birds sing in Spring?

Wikipedia Up here in the northern hemisphere spring has just started, bringing with it daffodils, sunlight and singing birds. But why do birds sing? They don’t have calendars like we humans do, so how do they know it’s time to start breeding? After all, it can’t be the weather, because where I live it’s been snowing today, but that hasn’t stopped the birds singing.

Scientists from Britain and Japan teamed up to solve this age-old problem. The result – birds sing not because of temperature changes or weather, but because of the lengthening days. As the days get longer, hormones are released which trigger the activation of a specific gene.

This gene gives the birds the urge to attract a mate and produce offspring – and just as humans gel their hair or wear make-up to attract a companion, birds are attracted to each other by singing. I suppose humans could sing to attract a mate, but somehow I don’t think it would be too likely to work. Just as giving a blackbird makeup probably wouldn’t inspire another blackbird to want to mate with it. But you never know…

Wikipedia Anyway, as always the big question is how on Earth did the scientists work out which gene was responsible? How did they know it was because of day lengths? Basically, they put a ‘genome chip’ in a sample of birds (Japanese Quails) to work out if any genes were activated or deactivated as the birds received varying amounts of sunlight each day.

They found that certain genes on the surface of the birds’ brains were switched on when the days were longer, and the cells with these genes then produced hormones that had already BBC Newsbeen known to give the birds the urge to mate. The result: birdsong, followed not too long afterward by baby birds.

It’s amazing to think how simple yet complicated nature can be sometimes. Interestingly, it is thought that humans may have genes affected by day lengths similar to those in the birds – these could be what causes some people to feel depressed in the winter.

Check out this great post on all things spring over on Exploratorium

Venus: The planet where it rains acid

Venus in visible light | Image: Wikipedia

Everyone seems to complain whenever it rains here on Earth, but on Venus you might actually have good reason to moan. Instead of water Venus’s clouds are made of corrosive sulfuric acid, and if you got covered in that, chances are you wouldn’t be around very long to tell the tale.

In reality it never rains sulfuric acid (at least not down to ground level) on Venus, because it evaporates before it has time to hit the ground – in fact, surface temperatures on Venus are hot enough to melt lead.

New research from ESA’s Venus Express probe is starting to reveal some of the secrets of Venus’s atmosphere, and some of them are very surprising indeed.

Unlike on Earth, where clouds tend to move only a few hundred miles at most, sulfuric acid clouds on Venus have ben seen moving from the poles to the equator, then back to the poles again, in just a few days.

Venus Express, which is due to end its mission in May 2009 | Image: ESABut wait a minute… where does all this sulfuric acid come from? After all, Venus is sometimes known as ‘Earth’s evil twin’ because of its runaway global warming, caused by excess carbon dioxide levels.

In fact, 97% of Venus’s atmosphere is made of CO2, although there are small amounts of gases such as sulfur dioxide and water vapor.

Recently discovered by the Venus Express probe is that the sulfuric acid is created when the sulfur dioxide and water vapor rise to the top of the atmosphere and are exposed to ultraviolet rays from the Sun, causing them to react and form sulfuric acid.

Why do they rise up? That’s one of the many things that remains to be found out, hopefully during this last year of the phenomenal Venus Express mission.

Click here for an interactive guide to Venus

Tornados rip through America’s South: 50+ dead

One of the tornados in Mississippi | Image: CNN i-Report

Super Tuesday will be remembered by most as the decisive day in the U.S. election campaign that was actually pretty indecisive, at least so far as the Democrats were concerned.

But for the families of the 50+ killed by unseasonal tornados in America’s south, Tuesday will certainly not be remembered as ‘super’. Ripping through Alabama, Arkansas, Kentucky, and Tennessee (which alone suffered 26 deaths), a trail of destruction that will take months and years to clean up was left by the deadly twisters. (map)

Fortunately America seems to be learning from the past about how to save lives: thanks to improved weather forecasting and the greater use of TV and radio to get the warnings out, countless lives were saved. Peter Dykstra does a nice analysis of how the media saved lives over on his CNN blog.

Searching through the remains of a home in Arkansas | Image: National GeographicSo what exactly causes tornados? It’s all down to air currents: when warm humid air collides with cold, dry air, the cold air is pushed above the warm air. This starts to create an updraft, and as this intensifies, a swirling motion begins. If the storm gets powerful enough, a funnel will touch down on the surface. Next, utter destruction. (Click here for America’s 10 deadliest tornados)

Click here for an excellent interactive guide detailing how tornados form.

UPDATE: These tornados were the deadliest in the U.S. in 20 years, according to CNN.

Snowstorms in China… what about global warming?

Snow blankets a forest in China | Image: National Geographic

Beautiful yet deadly. China’s worst snow in 50 years has already killed more than 65 people and delayed hundreds of thousands who wanted to get back for their only holiday of the year, the Lunar New Year. But it has also created beautiful scenes like the one above – evidence of the extraordinary power of nature to both kill and amaze.

The obvious question is “I thought the climate was getting hotter – why so much snow?” Climate change is a highly complex process, and ‘global warming’ can sometimes be a misleading term for this. (Click here for an interactive map of global warming effects)

One of the most noticeable effects of global warming will be more extreme weather – think of 2007: the California wildfires, the worst flooding in England since the 18th century, the water shortage in the southern US… it’s rapidly becoming clear that we ourselves will be the ones affected as the effects of climate change unfold before our eyes.

So although this individual storm in China is probably not climate change-related, events like this are likely to become far more common throughout this century. Hurricanes, tornadoes, floods, wildfires – even without wanting to be too much of a scaremonger, I think it’s safe to say we’re in for one wild century.

Just some of the hundreds of thousands who have been trapped by the snowstorms | Image: National Geographic