Earth Changes
It's the highest number of fatalities from tornadoes since 1953, when twisters killed 519 people, according to the National Oceanic and Atmospheric Administration (NOAA), the home agency of the National Weather Service.
As of Tuesday morning, the death toll from the devastating tornado that smashed through Joplin, Mo. on Sunday (May 22) had risen to 117, and could continue to rise as officials sort through the wreckage of the town, home to almost 50,000 people.
A tornado is a rotating column of air that stretches from the bottom of clouds to the Earth's surface. They can occur in a wide range of shapes and sizes, typically manifesting as a funnel of condensation surrounded by a cloud of dust and debris. Wind speeds in an average tornado reach more than 100mph (160km/h) and the system itself is less than 100 metres across, but extreme events can be several miles across, with wind speeds of more than 300mph.
It is difficult to relate any individual weather event to climate change and, unlike with hurricanes, there is little robust research on whether the warming planet is causing any noticeable effects. Grady Dixon, assistant professor of meteorology and climatology at Mississippi State University, told AFP: "If you look at the past 60 years of data, the number of tornadoes is increasing significantly, but it's agreed upon by the tornado community that it's not a real increase. It's having to do with better (weather tracking) technology, more population, the fact that the population is better educated and more aware. So we're seeing them more often."

Ryan Harper paused while looking for a missing friend after a devastating tornado hit Joplin, Mo. yesterday.
From the second floor, he watched the storm approach. The swirling rain began to form about a mile away.
Then the glass doors he was holding onto - with a 100-pound magnet to keep them locked - were suddenly pulled open. Pace was sucked outside briefly and then pushed back in like a rag doll, all the while clinging to the handles.
Yet despite warnings, watches and sirens, at least 116 people were killed when the twister roared through the southwestern Missouri city early Sunday evening. While insisting that forecasters' alerts went according to plan, the head of the National Weather Service said Monday that the plan -- and how it is communicated -- was not effective enough.
"I just ride down here, and I sit and look. I've been doing that for years anyway. I just look at the rivers. Just something to see for me," Nelson Hales said.
Nelson Hales has a sentimental attachment to the Ogeechee River. He's been fishing on the river since he was a little boy and was baptized in the water.
While rescuers scramble to dig out any remaining survivors from a weekend tornado that killed 116, residents in Joplin, Missouri, are bracing for the possibility of more tornadoes on Tuesday.
"There's no way to figure out how to pick up the pieces as is," Sarah Hale, a lifelong Joplin resident, said Tuesday. "We have to have faith the weather will change."
The National Weather Service warned there was a 45% chance of another tornado outbreak -- with the peak time between 4 p.m. and midnight Tuesday -- over a wide swath including parts of Texas, Oklahoma, Arkansas, Nebraska and Missouri.
Joplin is also in the area.
But if Monday's rescue efforts are any indication, even severe weather might not hamper the search for survivors.
City Manager Mark Rohr told reporters that more than 40 agencies are on the ground in the southwest Missouri city, with two first responders struck by lightning as they braved relentless rain and high winds searching for survivors.
By Monday night, they found 17 people alive. But many, including Will Norton, remain missing.
The 18-year-old was driving home from his high school graduation Sunday when the tornado destroyed the Hummer H3 he and his father were in.

May 21: Smoke plumes from the Grimsvotn volcano, which lies under the Vatnajokull glacier, about 120 miles east of the capital, Rejkjavik, which began erupting Saturday for the first time since 2004.
The country's main airport was closed and pilots were warned to steer clear of Iceland as areas close to the Grimsvotn (GREEMSH-votn) volcano were plunged into darkness Sunday evening.
Officials appeared to be responding to the ash with a radically different approach than last year, when European aviation authorities were sharply criticized for closing large swathes of airspace in response to the April 2010 eruption of another Icelandic volcano. Many airlines said authorities overestimated the danger to planes from the abrasive ash, and overreacted by closing airspace for five days. Thousands of flights were grounded, airlines lost millions of dollars and millions of travelers were stranded, many sleeping on airport floors across northern Europe.
Britain's Civil Aviation Authority spokesman Jonathan Nicholson said authorities had no plans to close airspace, even though an ash cloud classified by Met Office spokesman David Britton as high-density was expected to cover parts of Scotland by 6 a.m. local time (0500 GMT; midnight EDT) Tuesday.
The focus may soon be shifting from the epic flooding in the Mississippi Valley to Westwern states where enormous winter snows have piled up on mountain ranges.
More than 90 sites from Montana to New Mexico and California to Colorado have record snowpack totals on the ground for late May.

Louisiana wildlife officials Fred Kimmel, left, Travis Dufour, center, and Derrick Brasseaux check a soybean field for signs of wild animals fleeing rising floodwaters.
That unsurprising fact of nature has added a new complexity to the daily efforts of Travis Dufour, a Louisiana state wildlife biologist. He spends his days in a pickup truck, bouncing along levees and farm roads in search of displaced deer, black bears, alligators, wild turkeys, feral hogs and the occasional armadillo.
Mostly, Dufour rides herd on deer. It's his job to keep deer and people - and especially motor vehicles - from colliding as deer flee the impending Great Flood of 2011.









Comment: Here is another perspective on the 'Global Warming' issue: