Climate in the United States P. Lobosco Climate Regions of U.S. • Mediterranean • Marine West Coast • Moist Continental • Moist Subtropical • Desert • Steppe Division of Regions • The regions are divided based on temperature and precipitation. Mediterranean Region • The coast of California has a Mediterranean climate. The name comes from the area around the Mediterranean Sea. In the winter cyclones and moist maritime polar air masses bring heavy precipitation. In the summer there is almost no rain. Plant growth consists of shrubs and stunted trees. Agriculture is a major occupation. Marine West Coast Region • The northwestern coast of the United States has a marine west coast climate. This is a rainy climate because moist air from the Pacific rises and releases precipitation onto the Cascade Mountains. This produces mild winters and cool summers. The type of plant life that is common is the forest of needle-leaved trees, cedar, spruce, redwood and fir. The economy is based on lumber and paper. Moist Continental Region • The northern part of the United States extending from the Midwest to the Atlantic coast of the United States. Continental polar air masses flowing south produce very cold winters. In the summer the area receives warm tropical air masses. There are forests of broad-leaved trees and needle-leaved trees. Commercial agricultural is the main occupation. Moist Subtropical Region • The southeastern United States has a moist subtropical climate. Precipitation is higher and summers are hot due to maritime tropical air masses flowing inland. In the winter polar air masses mix with the maritime tropical and produce colder winters. The plant life consists of broad-leaved and needle-leaved trees, such as oak, chestnut and pine. Citrus fruits are grown in this region. Animal life includes herons, egrets, alligators, crocodiles and manatees. Desert and Steppe Region • Located within the western interior of the Untied States are two regions that similar climates. The desert and steppe regions begin east of the western mountain ranges and end in the Great Plains. Steppe receives slightly more precipitation. Plants, including yucca, and sagebrush grow in the desert. The steppe has short grass and scattered forests of needle- leaved trees. Grazing of livestock occurs here. Highlands (Variable) Region • These regions are located in the mountains. The climate varies with latitude and elevation. The temperature is low. Precipitation increases with elevation. Forestry is the major industry. Fir and pine grow here. Mountain areas are used for summer grazing for livestock from the Great Plains. Land Biomes • Climate determines plant life. • Plant life determines animal life. • Scientists classify areas with similar climates, plants and animals into divisions called biomes. Biomes of the U. S. • The major land biomes of the United States are: • tundras • coniferous forests • deciduous forests • tropical rain forests • grasslands • Deserts. Tundras • Tundras cover about 10% of the Earth’s surface. IN the United States they are only found in Alaska. The climate is extremely cold and dry. Tundras receive less than 25 centimeters of rain and snow. Almost 85% of Alaska if permafrost or frozen soil. Tundra Plant Life • Plant life on the tundra consists mainly of mosses and grasses. Lichen (algae and fungi growing together) cover the rocks and bare ground. Tall trees cannot grow. Tundra Animal Life • Lichens are the main food of caribou. • Wolves prey on caribou. • Birds such as ptarmigan and small animals such as lemmings inhabit the tundra. • Arctic terns are seasonal residents. Coniferous Forest • South of the tundra biomes are the coniferous forest biomes. The soil here thaws in the spring making the forest floor wet and swampy. A coniferous biome is also called a taiga. This biome can be found in parts of Alaska as well as at the higher elevations of the Rocky Mountains. The rainfall is between 50 and 125 centimeters and the temperature is cold. Coniferous Forest Plant Life • The trees that live in this biome are needle-leaved trees or conifers. Conifers produce their seeds in cones. They include firs, spruces and pines. Redwoods grow in Washington, Oregon and northern California. Southern California supports a coniferous biome known as a chaparral which consists of shrub like plants. Coniferous Forest Animal Life • Large animals in the coniferous forests include wolves, deer, black bears, grizzly bears and moose. Smaller animals such as beaver, hares, and red squirrels also live here. Crows and great-horned owls build nests among the conifers. Grouse roost in the branches. Deciduous Forests • South of the coniferous forest biomes are the deciduous forest. Deciduous forests begin at the northeastern border between the United States and Canada. The summers are warm and the winters cold. Rainfall is between 75-150 centimeters a year. Deciduous Forest Plant Life • Deciduous trees shed their leaves in the autumn. Oak, birch, maple, hickory and beech are the most common varieties found in the United States. In the spring wildflowers and ferns cover the forest floor. Deciduous Forest Animal Life • Many different animals make their home in deciduous forests. Thrushes, woodpeckers, cardinals and blue jays are birds that live in these forests. Snails, worms, snakes and salamanders live on the forest floor. Small mammals, such as squirrels and raccoons live in the branches of the trees. Tropical Rain Forest • In the United States, tropical rain forests are only found in Hawaii. Rainforests receive at lest 200 centimeters of rainfall a year. Temperatures are warm year round. Tropical Rain Forest Plant Life • Rain forests have more varieties of plant life than any other biome. Trees may grow to a height of 35 meters or more. High above the forest floor, the tops of trees met to form a canopy. The canopy is so thick that sunlight may not reach the forest floor for 10 minutes. Most plant grow in the canopy. Orchids and ferns grow on the branches of trees. Woody vines hang from trees. Tropical Animal Life • Animal life in the rain forest is rich and varied. Some rain forest animals spend their entire life in the trees and never touch the forest floor. Parrots, toucans and hundreds of other birds live in the trees. Insects, tree frogs and snakes crawl on the trunks and branches of trees. Bats hunt at night. Grasslands • The grassland biomes receive between 25 and 75 centimeters of precipitation a year. The grasslands of the Midwestern plains have hot summers and cold winters. Grasslands Plant Life • Grasses make up the main group of plants in this biome. There are few trees due to low rainfall. Fires, which occur often, prevent widespread tree growth. Today, most of the original grasslands have been replaced with pastures and farms. Wheat, corn and other grains are farmed on the Midwestern plains. Grasslands Animal Life • Gophers, prairie dogs, and other small animals live on the grasslands. Black birds, prairie chickens and meadow larks are some of the birds that feed on the grasshoppers, locusts and other insects. Bison and elk, large plant eaters, were once common. They were hunted by wolves and cougars. Since farms have replaced most of the grasslands, large animal live only in protected areas. Deserts Deserts • Deserts receive less than 25 centimeters of rain a year. Desert biomes in the United States are located in the Southwest. Although deserts can be hot or cold, the deserts of the southwestern Untied States are hot. Desert Plant Life • Plants that exist in the desert have adapted to a lack of rainfall. The fleshy stem of cacti help then to store water. Some can store up to a ton of water. Most flowering plants in the desert produce seeds and die within a few weeks due to lack of rainfall. Desert Animal Life • Like the plants, animals must be able to survive with very little rainfall. Plant eating animals such as jack rabbits and kangaroo rats obtain most of their water from the plants they eat. Meat-eating animals, such as cougars, obtain most of their water by eating the plant eaters. Most desert animals hide from the hot sun during the day and come out to eat only at night, when temperatures are cooler.
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