2. Climates and ecosystems

With the exception of Alaska and Hawaii, the United States lies within the easily developed and environmentally less-challenging temperate midlatitudes. Most of the country experiences relatively moderate conditions of weather and climate. With the exception of aridity, nearly all extremes are seasonal rather than lasting year-round. Even where nature imposes a challenge, such as in the arid West, settlers have found ways to make the land bountiful. Water storage and diversion, irrigation, air-conditioning, insulation, and artificial heating are just some of the ways in which Americans are able to adapt to the extremes that exist.

As mentioned previously, the United States is the only country that includes within its territory each of the world’s climates and ecosystems. At the extremes are frigid arctic con­ditions in northern Alaska, the steaming tropics of Hawaii, and the parched deserts of the Southwest. All other climates occur somewhere within the adjoining 48 states. Varied climatic conditions are important for several reasons. First and foremost, climate is the major control of ecosystems. Because of its many climates, the United States has a tremendous diversity of natural vegetation, animal life, soil conditions, and water features. Also, environmental diversity makes any human activity, including all types of farming, possible someplace within the country. Finally, if there is any truth to the statement “variety is the spice of life,” then Americans are indeed fortunate. A marvelous multitude of environments offers unlimited opportunities for development. Geographers identify, name, and classify climates and ecosystems in many ways. In the section that follows, the author uses descriptive terminology to the degree possible.

6. The Humid East

East of roughly the 100th meridian, the United States experiences a humid climate. In the Southeast, humid subtropical conditions prevail. Moisture is ample: Most locations receive 40 to 60 inches (100 to 150 centimeters) of precipitation per year and some places get considerably more. The Gulf Coast region, southern Florida, and portions of Appalachia receive 60 to 80 inches (150 to 200 centimeters). Severe drought is infrequent. With an annual average 55 inches (140 centimeters) of precipitation, Louisiana is the nation’s wettest state as measured by the statewide average of all recording stations. Moisture falls throughout the year, although a peak occurs during the summer months because of convectional thunderstorms. Winters tend to be mild. Freezing temperatures and snow are very rare in Florida and along the Gulf Coast. Temperatures drop and snowfall increases as one moves northward and inland from the moderating influence of the ocean. Summers are long, hot, and sauna-like due to the region’s high humidity.

The Northeast experiences a humid continental climate. Ample moisture is received throughout the year, although the total is slightly less than throughout most of the South. Driest conditions occur in the western portion of the region: Much of the Corn Belt receives an average 20 to 40 inches (50 to 100 centimeters) of moisture. Eastward, the amount increases: Coastal and upland areas receive 40 to 60 inches (100 to 150 centimeters) annually. Snowfall is common during winter months and can cover the ground from November through April (or even longer) in some northern areas. Annual amounts in excess of 100 inches (250 centimeters) are not uncommon, particularly in locations that receive “lake effect” snow (winds pick up moisture as they blow across the Great Lakes). Summer temperatures tend to be moderate, but winters can be frigid. Some northern locations have a January temperature average that ranges between 0 and 10°F (-12° to -18°C). The region does hold one weather-related record: A weather station atop New Hampshire’s Mount Washington experienced a sustained surface wind of 231 miles per hour (372 kilometers per hour), the highest straight wind velocity ever recorded on Earth’s surface. Under natural conditions, the eastern half of the United States supported a dense cover of broadleaf, needleleaf, or mixed forests. Today, much of the natural vegetation cover has been cleared for agriculture and other types of land use. In both climate zones, but particularly in the southeastern United States, a considerable amount of land that was once cleared for agriculture is being returned to woodland. Birds, marine life, and mammals large and small abound in the eastern United States. Conservation programs have actually increased many wildlife populations over what they were a century ago. As the country becomes increasingly urbanized, rural populations decline, thereby actually increasing wildlife habitat. Soils vary greatly in quality from place to place. In the far north, they tend to be thin, acidic, and generally poor. Throughout much of the South, soils were destroyed by poor agricultural practices. Corn Belt soils of the Midwest, however, are among the richest in the world.