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Climatic Regions of the United States, Semiarid
semiarid climate, angora goats, pronghorns, waterlogging, near freezing
The Semiarid climates are found in sections of the Great Plains regions, parts of Texas, New Mexico, the intermontane basin of Nevada, parts of eastern Washington and Oregon, and sections of neighboring states. This climate is a transitional one between the desert types and the humid types.
The temperature range is extreme. During winter the temperature can drop as low as -1° C (30° F). Summer temperatures often are in the upper 30°s C (lower 100°s F). Average temperatures vary across this large region extending from Canada to Mexico. For example, in eastern Washington state, January temperatures range from less than -7° C (20° F) to -1° C (30° F) and often drop down to -18° C (0° F). July averages are from 18° to 24° C (65° to 75° F). Temperatures are considerably higher in Las Vegas, Nevada, located at the southern end of the region. The average July temperature is 32° C (90° F) and the highest temperature ever recorded there was 48° C (118° F). The average high temperature in Las Vegas in January is in the lower 10°s C (lower 50°s F) and average lows are near freezing. Annual rainfall is from 250 to 500 mm (from 10 to 20 in), which is enough to support grasses but not enough to maintain a forest cover. Rainfall in the semiarid climate is sparse and unpredictable.
The region’s aridisol soil is alkaline and supports very sparse vegetation. With irrigation, it can support crops but not without encountering problems such as salt buildup and waterlogging. Despite these problems, the steppe grasslands are used for some grain cultivation. Hay and alfalfa are common agricultural products.
The steppe has a vegetation type consisting of short grasses occurring in sparse clumps or bunches. Scattered shrubs and low trees may also be found there. The steppe occupies vast regions of semidesert. Cattle, sheep, and angora goats are adaptable to the steppe, where they graze over vast acres of open range. Skunks, raccoons, coyotes, snakes, rodents, and pronghorns also inhabit the ecosystem.
America's Wheat Belt lies on the Great Plains. In the southern portion (Kansas, Nebraska, and Colorado) farmers sow winter wheat in the fall to be harvested in the spring. In the northern part (North Dakota, South Dakota and parts of Montana), where winters are more severe, farmers sow the seeds in the spring and harvest the crop in the fall.
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