Why do so many violent tornadoes form in the U.S. Central Plains?
The topography of the Central Plains of the United States is such that more tornadoes form there than in any other part of the world. Over these plains masses of warm moist air, caned tropical maritime air, sweep up from the Gulf of Mexico or the Caribbean Sea unhindered by mountain barriers. In spring, the warming earth of the Southern states adds to the layer of warm moist air traveling relatively close to the ground. At the same time there are frequent invasions of cool dry air masses riding high from the north or northwest. This is the maritime polar air from the northern Pacific Ocean which is blown eastward across the Rocky Mountains. Most of the moisture is dropped on the western s of the mountains, and the air that flows across the mountains becomes drier when it descends the eastern slopes. A tongue or wedge of cool dry air spreads out over the Great Plains states more than 10,000 feet above the earth’s surface, well ahead of the main block of cold air which drags behind, bloc