The third largest continent, extending from the narrow isthmus of Central America to the Arctic Archipelago. The physical environments of North America, like the rest of the world, are a reflection of specific combinations of the natural factors such as climate, vegetation, soils, and landforms. While the distribution of life-giving solar heat and water seemingly should determine the character and distribution of the natural regions, in reality the landforms modify the expected environmental patterns. In addition, human activities affect the quality of some environments, and natural hazards alter some regions permanently or semipermanently.