European climatic experience was not a very useful guide for survival in America. It was especially true in the subtropical South and the arid West. America’s western air comes not from the ocean, as in Europe, but from the continental interior which is extremely cold in the winter and ovenlike in the summer.
The main landmass of the United States is in the temperate zone. The climatic conditions of the country are determined by the great mountains and the wind. With every variation of surface it possesses every variety of climates, from that of the tropics (Hawaii), to that of the Arctic (polar) regions (Alaska). It is at the same time one of the hottest and one of the coldest, one of the wettest and one of driest countries in the world.
In the Northern Hemisphere, the western parts of continents are especially favored by the prevailing winds. This is because the western lands gather the rains as they come from the ocean, blown by storms that circle from west to east. This is an important factor in the climate conditions of the United States. The circulation of air from west to east does not take place in steadily blowing winds, but in cyclonic storms. In these storms, winds blow from all directions toward the center of the storm.
The Cascade Mountains and the Sierra Nevada Mountains, running from north to south, are so close to the west coast, that they catch the largest amount of the rain from the Pacific Ocean before it can go further inland. As a result, there is too little rain for almost the whole western half of the United States, which lies in the “rain shadow” of the mountains. In a great part of that territory, therefore, farmers must depend on irrigation water from the snows or rains that are caught by the mountains.
One of the most important geographical boundaries in the United States is the 50-centimetre rainfall line, which runs north and south almost through the middle of the country. East of the line, farming is relatively easy, and the population is relatively large. West of the line, one finds man-made irrigation systems, dry-farming, grazing and fewer people. West of the Rocky Mountains, running all the way from the Canadian border to Mexico, there are vast areas where almost no trees grow. In this section of the country are the deserts which receive as little as 12,7 centimetres of rainfall a year. Yet, west of the Sierra Nevada Mountains, there are places in which 250 centimetres of rain falls annually. It is one of the wettest places in the United States of America.
The location and vast sizes of landforms in the United States influence the region's climate zones and vegetation. Practically all types of the climate zones can be found in the United States.
A tropical rain-forest climate zone can be found in the Hawaiian Islands. Many of the islands remain warm and wet throughout the year. Although the state of Hawaii is located in tropical zone, its climate is comfortable because of the ocean currents that pass its shores and the winds that blow across the land from the northeast. The temperature usually remains close to the annual average of 24 degrees centigrade. The tropical-rain-forest vegetation includes broad-leaved evergreen trees and shrubs. A tropical-savanna climate zone can be found in the southern - most part of Florida. The wet and dry seasons encourage the growth of tall grasses.
A desert (arid) climate zone is located in the southwestern United States. This climate zone includes California's Death Valley, where summer temperatures can reach 54 °C. Desert vegetation includes many kinds of cactus plants. Steppe climate zones are found in the dry northern parts of the Great Basin and on the Great Plains. The vegetation in desert climate zones includes grasses and shrubs.
Further west, in the semi-arid region of short grass where farms and cattle ranches begin, the situation is very precarious. In years when rain is plentiful, the prairie grasses grow well and the herds of cattle grow fat. But during frequent droughts large herds of cattle suffer and may even die. Blazing summer heat dries up what little moisture is available, and in winter arctic temperatures and howling blizzards make life hard.
Humid subtropical climate zones are found in the southern and southeastern parts of the United States. Winter temperatures average between 7 °C and 16 °C, and the long summers are hot and humid. Areas near the Gulf of Mexico have heavy rainfall. Vegetation in humid subtropical climate zones includes forests of broad-leaved deciduous trees and evergreen trees. The climate is also good for a variety of valuable subtropical crops, such as indigo, rice, and cotton.
Ocean currents, winds and protective mountains along the Pacific coast help create a marine climate zone extending from northern California to the southern border of Alaska. Parts of these coastal areas receive more than 154 centimeters of rain each year. Dense forests of evergreen trees grow in the marine climate zone. The vegetation in northern California also includes giant redwood trees. Lands along California coast south of 40 °N latitude have a Mediterranean climate which makes this place a particularly alluring place. The combination of cool and pleasant summers and mild, not very rainy winters makes it possible to grow crops that will not mature anywhere else in the country. The result is that California has the most lucrative agricultural industry in America.
Continental climate zones cover most of the northern half of the central and eastern United States. The most southerly continental climate is a warm-summer zone that stretches from the Atlantic Ocean to the eastern part of the Great Plains. Forests of deciduous trees grow in many parts of the warm-summer zone, especially in lands east of the Mississippi River. Prairies spread over lands father west. A cool — summer zone lies north and northwest of the warm-summer zone. The vegetation consists mainly of mixed forests with both deciduous trees and needle-leaved evergreen trees.
Much of Alaska lies in a subarctic (subpolar) climate zone, which has very cold winters. In those parts of the state which lie above the Arctic Circle, Alaska still is a land of icebergs and polar bears. Ice masses lie buried in the earth, which is permanently frozen to a depth of 90 or more metres. From early May until early August the midnight sun never sets on this flat, treeless region, but the sun cannot melt the icy soil more than two thirds of a metre down. The Japan Current of the Pacific warms Alaska, and the Arctic cools it. Lands along the Arctic coastlines of Alaska lie in a tundra climate zone. Tundra vegetation consists of short grasses, mosses, and lichens.
The higher parts of Rocky Mountains and the Pacific ranges have mountain climates. Temperatures and vegetation vary with elevation. However, temperatures tend to be colder and vegetation more sparse in these highland areas than in the lands that surround them.
Seasonal weather conditions affect many people in the United States. Some types of storms may cross climate zones. For example, blizzards, or heavy snowfalls with high winds, may occur in the winter in the Great Plains, the Central Lowlands, the mountain areas, the Northeast, and the Far North. Tornadoes generally occur in the central and southern parts of the United States during spring and summer. Informally called «twisters», tornadoes are dangerous, because they can come about very quickly and have such violent, high winds. Hurricanes are another weather phenomenon that generally occur in areas along the Gulf of Mexico and the southern part of the Atlantic coast from late July through November.
Many areas of the country are subject of flooding. Usually flooding occurs when there is heavy rain in a short period of time, as during thunderstorms or hurricanes. Flooding also occurs when there is a sudden warm spell that melts large amounts of snow quickly. When spring floods are followed by heavy summer rains, whole towns can be wiped off the map.
Sometimes certain local weather conditions are improvements over the normal pattern for that climate zone. For example, a warm wind called the chinook blows down the slopes of the Rocky Mountains in winter and in early spring. This wind melts the snow at the base of the mountains, exposing grass for cattle grazing. Without the chinook, snow would remain on the ground longer.
The variations in temperature within the United States have had a marked effect on the country’s economy and living standards. As the Growing Season Map of the United States shows, there is a long crop-growing season along the southeast coast where winters are milder, and summers are hot. It was here that America first developed its reputation abroad as a land of plenty. This is also true in several small strips to the west where crops like grapes grow well during a large part of the year. In some of the cooler climates or in climates, which combine coolness and humidity, animals and products such as apples, wheat and corn are grown, thus giving the United States a large range of agricultural products. These pictures are typical of the north-eastern and eastern parts of the USA.
Thus, as we can see, the weather ranges from the warm, wet conditions of the Appalachians to the desert conditions of some of the western states. It varies from almost winterless climates in southern Arizona and southern Florida to long, very cold winters in Montana, North Dakota and South Dakota. In other words, the United States has practically all the climatic zones, the variety of which rewards those who is able of adapting to new circumstances. Vocabulary spell of the weather to expose humid
a land of plenty to circle temperate
blazing heat prevailing ovenlike
crucial line alluring tropical
arid precarious subarctic
sparse lucrative hurricane
crop – growing season to adapt to tornado blizzard flooding Comprehension Check Exercise I. Scan the text for answers to the following questions.
How does America's climate differ from that of Europe?
What kinds of climate zones are found in the region?
What is the major landscape for the northeastern part of the United States?
Why can farmers in the southeastern states generally grow a larger harvest than in any other place?
How do the climatic conditions influence the vegetation?
Does the climate influence weather? In what way?
Vocabulary Study Exercise I. Look up the following words in an English – English dictionary and write out the principal meanings: 1) adjacent a; 2) precarious a; 3) arid a; 4) alluring a; 5) expose v. Exercise II. Find in the text the English words and phrases corresponding to the Russian equivalents. 1) период хорошей погоды; 2) испепеляющая жара; 3) земля изобилия; 4) умеренный; 5) влажный климат; 6) заманчивый, соблазнительный; 7) скудная растительность; 8) прибыльный, выгодный, доходный; 9) случайный; ненадёжный, сомнительный; 10) умеренный климат; 11) преобладающий. Exercise III. Supply the words or word combinations from the text which correspond to the following. 1) highly attractive and able to arouse hope or desire; 2) to show, make visible or apparent; 3) water used to supply dry land by means of ditches; 4) to be around, to surround; 5) a place with an abundance of necessities and comforts; 6) uncertain, insecure, dependent on chance; 7) scorching hotness; 8) a period of indeterminate length (usually short) marked by some action or condition; 9) producing a good profit; 10) containing or characterized by a great deal of water vapor; 11) free from extremes; mild.
Exercise IV. Guess what natural disaster is meant by the following definitions:
A violent weather condition with winds 64-72 knots (11 on the Beaufort scale) and precipitation and thunder and lightening.
A severe tropical cyclone usually with heavy rains and winds moving a 73-136 knots (12 on the Beaufort scale).
A storm with widespread snowfall accompanied by strong winds.
A warm dry wind blowing down the eastern slopes of the Rockies.
A localized and violently destructive windstorm occurring over land characterized by a funnel-shaped cloud extending toward the ground.
A storm resulting from strong rising air currents; heavy rain or hail along with thunder and lightning.
Shaking and vibration at the surface of the earth resulting from underground movement along a fault plane of from volcanic activity.
The rising of a body of water and its overflowing onto normally dry land.
A violent rotating windstorm.
Exercise V. Match the correct climate with the following descriptions by placing the correct letter in the blank. A. Tropical-rain-forest E. Arid I. Subpolar
B. Tropical-savanna F. Semiarid J. Polar (arctic)
C. Humid subtropical G. Temperate K. Continental
D. Mediterranean H. Mountain Marine
______ 1. This climate is so old that the land is always frozen. No plants grow in this climate.
______ 2. This high-temperature climate has wet and dry seasons.
______ 3. Places with this climate have little or no rain and the highest daytime temperatures in the world.
______ 4. This high-temperature climate has heavy rainfall all year round.
______ 5. This climate, which is very pleasant to live in, occurs in California.
______ 6. Regions with this climate are very cold and have plenty of precipitation. In the summers, some thawing takes place, thus turning the land into a marsh.
______ 7. This climate, which has mild winters and humid summers, is ideal for forests, food crops, and fiber crops. Florida has this climate.
______ 8. Regions with this climate are affected by the moderating influence of the nearby ocean.
______ 9. Regions with this climate receive rainfall that is evenly spaced throughout the year. Temperatures are colder in winter and warmer in summer. The northeast part of the United States has this climate.
______ 10. The most important factor in this climate is the elevation of the land.
______ 11. This climate has a wet season and a dry season. Droughts often occur. Exercise VI. Use the clues to fill in the appropriate terms in the blanks. When you have finished, the circled letters will spell a factor that effects climate. The clue words: Japan, elevation, temperate, moderate, Humboldt, tropics, prevailing, marine, gulf, current, latitude, windward, monsoon, continental, arctic, mountains, climate, leeward.