| http://www.w3.org/ns/prov#value | - Some attain wind speeds of more than 300 mph (480 km/ h), stretch more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 km).[1][2][3] Although tornadoes have been observed on every continent except Antarctica, most occur in the United States.[4] They also commonly occur in southern Canada, south-central and eastern Asia, east-central South America, Southern Af
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