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| Why was the Oklahoma tornado so dangerous? | Why was the Oklahoma tornado so dangerous? |
| (about 3 hours later) | |
| What is a tornado? | What is a tornado? |
| Tornados form under "supercell storms", which are very active cumulonimbus thunderstorm clouds. Beneath supercells, air rises rapidly through the atmosphere, and through a shearing process begins to rotate and form a tornado vortex. | Tornados form under "supercell storms", which are very active cumulonimbus thunderstorm clouds. Beneath supercells, air rises rapidly through the atmosphere, and through a shearing process begins to rotate and form a tornado vortex. |
| How powerful was the Oklahoma tornado? | How powerful was the Oklahoma tornado? |
| Tornadoes are measured on the Enhanced Fujita (EF) scale from zero (weak) to five (very strong). The UK Met Office said the tornado that struck Moore city in Oklahoma on Monday was EF5. The power of tornadoes is often estimated after the event by assessing the devastation left behind. | Tornadoes are measured on the Enhanced Fujita (EF) scale from zero (weak) to five (very strong). The UK Met Office said the tornado that struck Moore city in Oklahoma on Monday was EF5. The power of tornadoes is often estimated after the event by assessing the devastation left behind. |
| How large was the tornado? | How large was the tornado? |
| The width of the spinning air column varied from 100 metres to around two miles (3km). | The width of the spinning air column varied from 100 metres to around two miles (3km). |
| How common are big tornadoes? | How common are big tornadoes? |
| Moore has been struck by major tornadoes at least four times in the past 15 years, in 1999, 2003, 2010, and on Monday. The 1999 storm featured the strongest winds ever recorded, at 317mph. | Moore has been struck by major tornadoes at least four times in the past 15 years, in 1999, 2003, 2010, and on Monday. The 1999 storm featured the strongest winds ever recorded, at 317mph. |
| Why are tornadoes common in the region? | Why are tornadoes common in the region? |
| The stretch of land through Nebraska, Oklahoma and Texas is known as Tornado Alley for a reason. Here, the environment is perfect for spawning supercells and tornadoes. They form when cool and dry air that blows over the Rocky Mountains meets warm and moist air from the Gulf of Mexico. | |
| Why was this tornado so dangerous? | Why was this tornado so dangerous? |
| The tornado was one of the most powerful ever seen, but other factors combined to make it so devastating. It touched the ground for 45 minutes, which is long for a tornado, and did so in an urban area, when schools and offices were filled. | The tornado was one of the most powerful ever seen, but other factors combined to make it so devastating. It touched the ground for 45 minutes, which is long for a tornado, and did so in an urban area, when schools and offices were filled. |
| Are tornadoes getting stronger with climate change? | Are tornadoes getting stronger with climate change? |
| "Tornadoes are too small-scale for current climate models to simulate, so it is not possible to say very much about how strength and occurrence might alter under climate change. But climate change means warmer temperatures and more moisture and that is providing more energy for the types of storms that produce tornadoes in a warmer climate," says Suzanne Gray at Reading University. | "Tornadoes are too small-scale for current climate models to simulate, so it is not possible to say very much about how strength and occurrence might alter under climate change. But climate change means warmer temperatures and more moisture and that is providing more energy for the types of storms that produce tornadoes in a warmer climate," says Suzanne Gray at Reading University. |
| Does the UK get tornadoes? | Does the UK get tornadoes? |
| About 30 to 40 tornadoes strike Britain each year, but they are far weaker and shorter-lived than those in the US. They cause little or no damage. A rare exception was the tornado that hit Birmingham in 2005, which damaged trees, houses and cars, and injured 19 people. | About 30 to 40 tornadoes strike Britain each year, but they are far weaker and shorter-lived than those in the US. They cause little or no damage. A rare exception was the tornado that hit Birmingham in 2005, which damaged trees, houses and cars, and injured 19 people. |
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