If that happens, the wind will assist. The wind, regularly whirled into tornadoes, is the other signature of the southern plains, and that flatness encourages it. Cold air floods down from Canada, with nothing to block its path; hot air floods up unhindered from the Gulf of Mexico. Then, from the west, both the polar jet stream and the subtropical jet stream stir by, like fingers flicking the edges of a pinwheel, kicking off the rotation. Solid, stable, whipped by winds—the heart of flatness. But the prairie is as diverse as a rain forest, and just as beautiful.