8th March 2014 Giant walls could eliminate tornadoes A series of giant walls – stretching up to 100 miles along the U.S. "Tornado Alley" – could prevent such disasters from happening in the future, according to physicists.
The idea is vaguely reminiscent of Mega City One, a fictional city-state in the Judge Dredd universe. The outer walls of Mega City One spanned vast distances – protecting residents from potential weather or environmental disasters outside. Now researchers believe a structure of similar appearance and scale might become a reality in the not-too-distant future. Running from east to west, several 1,000 ft (300 m) high walls – in Kansas, Louisiana, North Dakota, Oklahoma and Texas – could dampen the effects of tornadoes. In the American Midwest, these violent weather events are caused by intensive encounters between northbound warm air flows and southbound colder air flows. By deploying "great walls" at a number of strategic locations (determined by computer modelling), it might be possible to disrupt the formation of twisters and prevent them from gaining momentum. The concept has been put forth by Prof Rongjia Tao of Temple University, Philadelphia and was discussed this week at the American Physical Society in Denver. Tao claims the project would cost about $16bn (£9.6bn), but in the long term would save many billions of dollars more in terms of protecting buildings and infrastructure. It could prove an especially useful adaptation measure when considering the rapid increase in disasters from climate change. The Moore tornado that struck Oklahoma last year was among the costliest tornadoes in U.S. history (adjusted for inflation), with peak winds of 210 mph (340 km/h) causing $2bn in damage, killing 25 people and injuring 400 others. Some meteorologists estimated that the energy released by the storm was over 600 times greater than the atomic bomb dropped on Hiroshima.
As evidence for his theory, Professor Tao has cited the flat plains of China, which are broken up by east-west hill ranges. Despite being only a few hundred metres high, these have a dampening effect on air currents, with only three tornadoes occurring in the region last year, compared to 803 in the U.S. A similar effect is seen in parts of America, as Tao explains: "Washington County is a tornado hotspot. But just 60 miles (100 km) away is Gallatin County, where there is almost no risk. Why? Just look at the map – at Gallatin you have the Shawnee Hills." Like the hills in China, these are only 200-250 m (650-820 ft) in height, but have a major influence on weather patterns. Computer models have already been demonstrated by Tao and his team. The next step is to build physical models for testing in wind tunnels. No government or environmental agencies have yet been contacted, but if this megaproject ever became a reality, he is confident it would be technically and financially viable. Rather than being eyesores – like the monolithic walls of Mega City One – they could also be designed in a visually attractive way. "I spoke to some architects and they said it's possible," he added. "It would take a few years to finish the walls but we could build them in stages."
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