Chapter 5 Study Guide for Apollo Team

Chapter 5 Study Guide for Apollo Team

The Physical Geography of the US and Canada

Landforms (page 115) Many different landforms are found in Canada and the United States.

A.  The Rocky Mountains link the United States and Canada.  These mountains stretch more than 3,000 miles from New Mexico to Alaska.  The Pacific Ranges and the Rocky Mountains formed as a result of collisions between the Pacific and North American tectonic plates millions of years ago. Mt. McKinley in Alaska is the highest point in North America.

B.  Dry basins and plateaus are found between the Pacific Ranges and the Rocky Mountains.  The Colorado Plateau has been eroded by the Colorado River to form the Grand Canyon.  The Great Basin includes Death Valley—the hottest and lowest place in the United States. Canada’s Nechako Plateau and Fraser Plateau are narrower than the plateau areas in the United States.

C.  The Great Plains are located east of the Rockies and extend 400 miles across the center of the region.  They slope downward to the Central Lowlands along the Mississippi River.

D.  The Eastern Mountains includes the Canadian Shield and the Appalachian Mountains.  The Canadian Shield is a giant core of rock that anchors North America.  The Shield makes up the eastern half of Canada and the northeastern United States.  The Appalachian Mountains are North America’s oldest mountains.  They extend 1,500 miles from Quebec to central Alabama.

E.  Coastal Lowlands lie east and south of the Appalachians.

F.  Islands are important to the region. Manhattan Island at the mouth of the Hudson River is a major world economic center. Hawaii formed by volcanic mountaintops in the Pacific Ocean. Canada’s main islands in the east include Newfoundland, Prince Edward Island, and Cape Breton Island. In the west is Vancouver Island.

A Fortune in Water (page 116) Abundant freshwater lakes and rivers help the United States and Canada to satisfy the water needs of cities and rural areas, provide power for homes and industries, and move resources across the continent.

In North America the high ridge of the Rockies is called the Continental Divide or Great Divide. A divide is a high point or ridge that determines the direction that rivers flow. East of the Continental Divide, the rivers flow toward the Arctic Ocean, Hudson Bay, the Atlantic Ocean, and the Gulf of Mexico. West of the Continental Divide the rivers flow toward the Pacific Ocean. Some rivers have their headwaters, or source, in the Rockies. Many tributaries, or brooks, rivers, and streams, flow into these rivers.

The Mississippi River is North America’s longest river at 2,350 miles. It stretches from Minnesota to the Gulf of Mexico. It is one of the world’s busiest commercial waterways. The St. Lawrence River is one of Canada’s most important rivers. It is in eastern Canada. Quebec, Montreal, and Ottawa all lie along the St. Lawrence River.

In the eastern United States, a boundary called the fall line marks the place where the higher land of the Piedmont drops to the lower Atlantic Coastal Plain. Eastern rivers become rapids and waterfalls along the fall line. Many important U.S. cities—Philadelphia, Baltimore, and Washington D.C., are along the fall line. These cities have port facilities for ocean- going ships. In the Northeast and the South the waterpower of the falls is used for textile mills and factories. Niagara Falls, along the Canada-United States border, is a tourist area and a major source of hydroelectric power for both countries.

In Northern Canada, Glacial dams created Great Bear Lake and Great Slave Lake.  Glaciers also created the Great Lakes in the central section of the continent. The Great Lakes-St. Lawrence Seaway is a series of canals, rivers, and other inland waterways linking the Great Lakes with the Atlantic Ocean. This link has been important to the economic development of North America.

Natural Resources (page 119) The geological processes that shaped the landscape of North America also gave the region a great variety of resources:

A.  Fuels include petroleum, natural gas, and coal.

B.  Mineral resources include gold, silver, copper, iron ore, nickel, and potash—a mineral salt used in fertilizer.

C.  Timber is an important resource for both countries. However, today forests cover less than 30 percent of the United States and 50 percent of Canada. Efforts to harvest the timber responsibly include planting new trees, protecting animals in forests, and preserving old-growth forests.

D.  Fishing is important to the region.  Some fisheries, or places for catching fish and other sea animals, have been overfished and are now regulated by governments.

Climate and Vegetation

In the last section, you read about the physical geography of the United States and Canada. This section focuses on the climate regions and natural vegetation in the region.

Terms to Know

timberline -The elevation above which trees cannot grow (page 123)

Chinook - A warm, dry wind that blows down the Rocky Mountains in late winter and early spring (page 124)

prairie - A naturally treeless expanse of grasses (page 124)

Super-cell - A violent spring and summer thunderstorm that causes a tornado (page 124)

hurricane -  An ocean storm hundreds of miles wide with winds of 74 miles per hour or more (page 125)

blizzard - A long, severe snowstorm (page 125)

Introduction (page 121) The climate regions and natural vegetation of the United States and Canada are diverse.

A Varied Region (page 121) Much of the United States and Canada have climates that match their latitudes. Most of Canada and Alaska are in high latitudes, so they experience long, cold winters and short, mild summers. Most of the continental United States and the southern one-third of Canada lie in more temperate latitudes where the climate regions vary with elevation. Hawaii has a predominantly tropical climate.

Northern Climates (page 122) There are two northern climate zones:

A.  The subarctic climate zone covers large parts of Canada and Alaska. The winters are very cold and the vegetation is mostly coniferous forest.

B.  The tundra climate zone is found in lands along the Arctic coastline.  This zone has very cold winters and cool summers. Most plants cannot live there. Greenland’s tundra vegetation is sedge, cotton grass, and lichens. Some small trees and scrubs can grow there. Few people live in this climate zone.

Western Climates (page 122) The climate and vegetation patterns in the western areas of the United States and Canada vary widely. This is because of the combined effects of latitude, elevation, ocean currents, and rainfall.

A.  A marine west coast climate zone is found along the Pacific coast from northern California to southern Alaska.  The mix of ocean currents and winds with the Pacific Ranges causes this climate.  The mountains force the wet ocean air upward where it cools and releases its moisture. This area receives more than 100 inches of rain each year. Coniferous trees, ferns, and mosses are common.

B.  A Mediterranean climate zone is found in southern California.

C.  A desert climate zone is found between the Pacific Ranges and the

Rocky Mountains.  The rain shadow effect keeps the plateaus and basins in the area hot and dry.  This climate supports cacti. During brief spring rains, hardy wildflowers bloom.

D.  A steppe climate zone is also found between the Pacific Ranges and the Rocky Mountains.  The steppe climate is usually in areas near deserts. Desert scrub, grasslands, or coniferous forests grow in this steppe climate, depending on latitude.

E.  A highland climate is found in the higher elevations of the Rocky Mountains and Pacific Ranges. Coniferous forests cover the middle elevations of the western mountains. Beyond the timberline, the elevation above which trees cannot grow, only lichens and mosses grow in the constant cold. In the late winter and early spring, a warm, dry wind called the Chinook may blow down the eastern slopes of the Rockies.  This wind quickly melts and evaporates the snow at the base of the mountains.

Interior Climates (page 124) The Great Plains of the United States and Canada are far from large bodies of water which moderate climate. This area is a humid continental climate zone with bitterly cold winters and hot summers. Prairies, or naturally treeless expanses of grasses, cover the land. In the Great Plains and Eastern United States, super-cells, or violent spring and summer thunder- storms, create tornadoes. The Great Plains supply most of North America’s wheat harvest.

Eastern Climates (page 125) There are two eastern climate zones in the region.

A.  A humid subtropical climate zone with long, humid summers and mild winters is found in the southeastern part of the region. Deciduous forests grow there.  Wetlands and swamps in the area are home to a great variety of vegetation and wildlife. Hurricanes, or ocean storms hundreds of miles wide with extremely strong winds, are common during the late summer and early autumn.

B.  A humid continental climate zone extends from northeastern United States into southern Canada. Deciduous and mixed deciduous-evergreen forests grow in this climate zone. In winter, much of northern North America has blizzards. These snowstorms have winds over 35 miles per hour, temperatures below freezing, and visibility of less than 500 feet.

Tropical Climates (page 125) There are two tropical climate zones in the United States.

A.  A tropical savanna climate zone is found in the southern tip of Florida.

B.  A tropical rainforest zone is located in Puerto Rico and Hawaii.

Chapter 4 Study Guide for Apollo Team

Chapter 4 Study Guide

Chapter 4, Section 1

More than 7 billion people live on Earth, inhabiting about 30 percent of the planet’s land.

Scientists use statistics to learn about population growth.  The birthrate is the number of births per year for every 1,000 people. The death rate is the number of deaths per year for every 1,000 people. Natural increase is the difference between an area’s birthrate and its death rate. Migration must also be considered when examining population growth. The demographic transition model uses birthrates and death rates to show changes in population trends of a country or region.  A high birth rate combined with a low death rate reduces doubling time, the number of years it takes a population to double in size.

Populations that grow rapidly use resources more quickly.  The world’s population is unevenly distributed by age, with the majority of some countries’ populations being infants and young children.

Some countries have experienced negative population growth, in which the annual death rate exceeds the birthrate.

Just as the world’s population growth rate varies among the Earth’s regions, the planet’s population distribution, the pattern of human settlement, is also uneven. Only about 30 percent of the Earth’s surface is made up of land. Much of that land is not fit to live on. Almost everyone on Earth lives on a little less than one-third of the planet’s land.  Europe and Asia are the most densely populated continents.

Where populations are highly concentrated, many people live in metropolitan areas.

To find out how crowded a place is, geographers measure population density, which is the total population of a country divided by its total land area. Two countries with the same number of people may not have the same population density. For example, Bolivia and the Dominican Republic have similar populations, but the Dominican Republic has a smaller land area, and so it is more densely populated than Bolivia.  Because the measure of population density includes all the land area of a country, it does not account for uneven population distribution within a country. 

Many people are moving from city to city, suburb to suburb, and from rural areas to cities. The growth of city populations because of migration is called urbanization.  When people emigrate from the country of their birth, they are known as emigrants in their homeland and called immigrants in their new country. People who flee their country because of wars, food shortages, or other problems, are called refugees.

Chapter 4, Section 2

Cultures may also include people who belong to different ethnic groups. Governments maintain

order, provide protection from outside dangers, and supply other services to people. Governments are organized according to levels of power and by the type of authority.  Geographers look at economic activities to study how a culture uses natural resources and to analyze the ways in which people obtain, use, and sell goods and services. Geographers divide the Earth into culture regions, which include countries.

 Culture is the way of life of a group of people who share similar beliefs and customs. People communicate information and experiences and pass on cultural values and traditions through language. Large groups of languages having similar roots are called language families. In many cultures, religion

enables people to find a sense of identity. In every culture, members of society fall into various smaller social groups. In all cultures, the family is the most important group. Most cultures are also made of social classes that may share similar economic systems, forms of government, and social groups.

The process of spreading new knowledge from one culture to another is called cultural diffusion.

The earliest humans were nomads. About 10,000 years ago, many of these nomads became farmers. This shift from gathering food to producing food is known as the Agricultural Revolution.

By about 3500 B.C., some of these early farming villages evolved into civilizations.

The world’s first civilizations are known as culture hearths.  The most influential culture hearths developed in areas that make up the modern countries of Egypt, Iraq, Pakistan, China, and Mexico. Each of these areas started as farming settlements, and had a mild climate and fertile land. The areas were each located near a major river or source of water, and the people irrigated the land and were able to grow surplus crops.

Because more food was available, fewer people farmed the land. People created new technology and carried out specialized economic activities that spurred development of long-distance trade. Wealth from trade led to the rise of cities and complex social systems. The ruler of a city needed an organized government.

Officials and merchants created writing systems to record and transmit information.  Ideas and practices spread through trade and travel, and through migration. Migrants often blend their cultures with

those of the people in the migrants’ adopted countries.  Cultural diffusion has increased rapidly during the last 250 years. In the 1700s and 1800s, industrialized countries began to mass-produce goods, and their economies changed dramatically. This development, known as the Industrial Revolution, led to social changes.

At the end of the 1900s, the world experienced the information revolution. Computers now

make it possible to store huge amounts of information and send it all over the world instantly, linking cultures of the world more closely than ever before.

Chapter 4, Section 3

A unitary system of government gives all key powers to the national or central government. A federal system divides the powers of government between the national government and state or provincial governments. Another similar type of government structure is a confederation, a loose union of independent territories. In an autocracy, such as a totalitarian dictatorship or a monarchy, the power and authority to rule belong to a single individual. An oligarchy is any system of government in which a

small group holds power.

A democracy is any system of government in which leaders rule with the consent of the citizens.  Democratic countries have representative democracies, in which the people elect representatives. Many democratic countries, such as the United States and France, are republics, in which voters elect all major officials. The head of government is usually a president elected for a specific term.  Not every democracy is a republic. The United Kingdom is a democracy with a monarch as head of state. This monarch’s role is ceremonial, and elected officials hold the power to rule.  All economic systems make three basic economic decisions:

(1) what and how many goods and services should be produced,

(2) how they should be produced,

(3) who gets the goods and services that are produced.

In a traditional economy, habit and custom determine them rules for all economic activity. In a market economy, individuals and private groups make decisions about what to produce. A market economy is based on free enterprise, the idea that individuals have the right to own property or businesses and make a profit with only limited government interference. Another term for an economic system organized this way is capitalism.

A mixed economy is one in which the government supports and

regulates free enterprise through decisions that affect the marketplace.  The government works to keep competition fair and to work for the benefit of the people.  A command economy is one in which the government owns or directs the means of production and controls the distribution of goods. Countries with command economies try to distribute goods and services equally among all citizens.

Communism requires strict government control of almost the entire society, including the economy.

Socialism allows a wider range of free enterprise alongside government-run activities. The main goals of socialism are:

(1) equal distribution of wealth and economic opportunity;

(2) society’s control of all major decisions about production; and

(3) public ownership of most land, factories, and other means of production. Some socialist countries, like those in Western Europe, are democracies. Under democratic socialism, people elect their political leaders.

Chapter 4, Section 4

Elements from the Earth that are not made by people but can be used by them for food, fuel, or other necessities are called natural resources. Renewable resources cannot be used up or can be replaced naturally or grown again in a relatively short amount of time. Nonrenewable resources, such as minerals and fossil fuels, cannot be replaced. Because fossil fuels and other nonrenewable resources cannot

be replaced, they must be conserved. Environment experts have encouraged people to replace their dependence on fossil fuels with the use of renewable energy resources including hydroelectric

power, solar energy, and nuclear energy.

Primary economic activities involve taking or using natural resources directly from the Earth. Secondary economic activities use raw materials to produce something new and more valuable.

Tertiary economic activities provide services to people and businesses. Quaternary economic activities are concerned with the processing, management, and distribution of information.

Economic activities, including industrialization, or the spread of industry, influence a country’s level of development.  Countries with much technology and manufacturing are called developed countries. Newly industrialized countries have moved from primarily agricultural to primarily manufacturing

and industrial activities. Countries working toward greater manufacturing and technology activities are called developing countries.

The unequal distribution of natural resources and differing labor costs and education levels promote a complex network of trade among countries. Some governments add barriers to trade to help their own

economy. Barriers may include adding a tariff, or tax, to the price of imported goods, putting a quota, or number limit on importing a particular product from a particular country, or imposing an embargo, banning trade with another country altogether.

Free trade is the removal of trade barriers so that goods can flow freely among countries.

Pollution is the release of unclean or impure elements into the air, water, and land.  Earth’s bodies of water normally renew themselves, but can be polluted when oil tankers and offshore drilling rigs cause oil spills; when chemical waste enters the water supply; and when fertilizers and pesticides seep into groundwater.

Land pollution occurs when chemical waste poisons topsoil, or when solid waste is dumped in

landfills. Radioactive waste and toxic runoff can also leak into the soil.

The main source of air pollution is the burning of fossil fuels.  Burning fuel gives off poisonous gases. Acidic chemicals in air pollution also combine with precipitation to form acid rain. When forests

are destroyed by acid rain, less oxygen is produced by photosynthesis.  As humans expand their communities, they threaten natural ecosystems. Because the Earth’s land, air, and water are interrelated,

what harms one part of the system harms all the other parts.

Chapter 3 Study Guide

Name

Date

Class

Chapter 3 STUDY GUIDE

For use with textbook pages 55–58.

Earth-Sun Relationships Chapter 3, Section 1

Terms to Know

weather The condition of the atmosphere in one place and time (page 55)

climate The weather patterns an area experiences over a long period of time (page 55)

axis An imaginary line running through the planet’s center from north to south (page 56)

temperature The measure of how hot or cold a place is (page 56)

revolution Trip around the sun (page 56)

equinox A day when the daylight and night- time hours are equal in length (page 57)

solstice A day with the longest or shortest period of daylight in a year (page 57)

greenhouse effect The trapping of heat from the sun by the atmosphere that prevents all the heat from escaping into space (page 58) global warming A general rise in global temperatures (page 58)

Introduction (page 55) The relationship between the earth and the sun influences all of life on Earth. Scientists study changes in this relationship.

1.          What does the relationship between the earth and the sun influence?

Climate and Weather (page 55) Weather is the condition of the atmosphere in one place at a particular time. Climate is the pattern of weather that an area experiences over a long period of time. The most important influence on the climate of an area is the earth’s position in relation to the sun. The sun’s heat and light do not reach all parts of the earth at the same time or with the same strength.

2.          What is the difference between weather and climate?

Earth’s Tilt and Rotation (page 56) The earth’s axis is an imaginary line running from the North Pole to the South Pole through the earth’s center. The earth is tilted on the axis at an angle of 231⁄2 ̊. Because of the tilt, different places on Earth receive direct sunlight at various times of year. The angle of the tilt affects the temperature—or how hot or cold a place is. Areas that get a large amount of direct sunlight have warmer temperatures than places that receive little direct sunlight.

Earth rotates on its axis, making one complete rotation every 24 hours. The part of the earth that faces the sun has light. The side facing away from the sun has darkness.

3.          How do tilt and rotation affect Earth?

Earth’s Revolution (page 56) The earth travels in an orbit around the sun. It takes 365 days—one year—to complete one revolution, or trip around the sun. The revolution of the earth and its tilt cause changes in the angle and amount of sunlight that reach different places. These changes cause seasons. The length of daylight and the daily temperatures change as the seasons change. On about March 21 and September 23 each year, the sun’s rays fall directly on the Equator. This event is known as an equinox because there are equal daylight and nighttime hours.

4.          What causes seasons on Earth?

The Tropics of Cancer and Capricorn (page 56) The Tropic of Cancer at 231⁄2 ̊N is the northernmost point on Earth to receive the direct rays of the sun. The direct rays reach the Tropic of Cancer on about June 21. This day is known as the summer solstice because it is the longest day of sunlight in the Northern Hemisphere. It is the beginning of summer there.

The Tropic of Capricorn at 231⁄2 ̊S is the southernmost point on Earth to receive the direct rays of the sun. The direct rays reach the Tropic of Capricorn on about December 22. This is known as the winter solstice because it is the shortest day of sunlight in the Northern Hemisphere. It is the beginning of winter there.

5.          What causes the beginning of summer and of winter in the Northern Hemisphere?

The Poles (page 57) The amount of sunlight at the poles changes greatly throughout the year.

When one Pole is tilted toward the sun, it receives continuous sunlight for six months. At the same time, the other Pole is tilted away from the sun and receives no sunlight at all for six months.

6.          Why does one Pole receive sunlight when the other Pole receives no sunlight at all?

The Greenhouse Effect (page 58) The earth’s atmosphere acts as a screen for the sun’s radiation. When rays from the sun reach the atmosphere, some of them are reflected back into space, but some of them pass through to the earth’s surface. The radiation that reaches the surface is then reflected back into the atmosphere. On its way back out through the atmosphere, some of the radiation passes into space, and some of it gets reflected back to earth again. This process is known as the greenhouse effect, because it traps heat the same way a greenhouse does.

The part of the atmosphere that traps the heat from the earth is made up of carbon dioxide (CO2) and water vapor. In recent years the burning of fossil fuels has caused the amount of CO2 in the atmosphere to rise rapidly. An increase in CO2 levels causes the atmosphere to trap more heat. This in turn causes a general rise in global temperatures, or global warming. Global warming can cause ice caps and glaciers to melt and cause a rise in sea levels.

Factors Affecting Climate Chapter 3, Section 2

For use with textbook pages 59–64.

Terms to Know

prevailing wind Global wind that blows in a fairly constant pattern (page 62)

Coriolis Effect The effect of the earth’s rotation on prevailing winds and currents (page 62) doldrums A narrow band of windless area at the Equator (page 62)

current A stream of water moving through a body of water in a certain direction (page 62)

El Niño A periodic reversal of the pattern of ocean currents and water temperatures in the mid-Pacific region (page 63) windward The side of a mountain range facing the wind (page 64)

leeward The side of a mountain range that does not face the wind (page 64)

rain shadow The dry area found on the lee- ward side of a mountain range (page 64)

Climate Factors

Introduction (page 59) Latitude, wind and water patterns, and landforms combine with the earth- sun relationship to influence world climates.

Latitude and Climate (page 59) The climate follows general patterns within each latitude zone. There are three latitude zones:

Chapter 3, Section 2

A.  Low latitudes- between the Tropic of Cancer and the Tropic of Capricorn, receive direct rays of the sun year-round. Low latitudes have warm to hot climates.

B.  High latitudes are at the earth’s north and south polar areas—north of the Arctic Circle and south of the Antarctic Circle.  When either pole is tilted toward the sun, it receives continuous indirect sunlight for about six months.  At the same time the opposite polar region is tilted away from the sun and receives continuous darkness. High latitudes have cool to very cold climates.

C.  Mid-latitudes are located between the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere and between the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere. The mid-latitudes generally have temperate climates with more dramatic seasonal weather changes than high or low latitudes.

Elevation and Climate (page 61) The earth’s atmosphere becomes thinner as altitude increases. Thinner air keeps less heat, so temperatures are generally cooler at higher elevations.

Wind and Ocean Currents (page 61) Winds distribute the sun’s heat around the earth. Global winds blow in fairly constant patterns called prevailing winds. The earth’s rotation causes winds to blow diagonally from the Equator. This is known as the Coriolis Effect. Low latitude winds are called trade winds, because they were travelled on by ships involved in trade. Mid-latitude winds are called Westerlies because they blow from the west. High latitude winds are called polar easterlies because they push cold air from east to west toward the mid-latitudes. At the Equator there is a narrow band of generally windless area called the doldrums.

Cold and warm streams of water, called currents, move through the oceans. The Coriolis Effect causes ocean currents to move in clockwise circles in the Northern Hemisphere and counterclockwise circles in the Southern Hemisphere. Ocean currents bring cold water from the polar areas toward the Equator. The water warms as it moves through the Tropics and forms warm ocean currents. Cold ocean currents cool the lands they pass. Warm ocean currents warm the lands they pass.

The water cycle also affects weather. Water vapor forms in the atmosphere from evaporated surface water. As colder temperatures cool the rising air, the vapor forms clouds. Further cooling causes rain to fall, which can lower the temperature on warm days.

Climate is affected by recurring events, such as El Niño. This is a periodic reversal of the pattern of ocean currents and water temperatures in the mid-Pacific region. El Niño influences climates throughout the world. In an El Niño year, precipitation increases along the coasts of North and South America, increasing the risk of floods. In Southeast Asia and Australia, El Niño causes droughts and sometimes forest fires.

Landforms and Climate (page 63) The presence of landforms such as continents can affect climate. Large bodies of water are slower to heat than land, so water temperatures change less than land temperatures. As a result, coastal lands experience less changeable weather than inland areas.

Mountains can also affect climate. Winds that blow over an ocean are pushed upward when they meet a mountain range. The rising air cools, and precipitation is released on the mountain’s windward side—the side of facing the wind. After the precipitation is released, winds get much warmer and drier as they go down the opposite, or leeward, side of mountains. The hot, dry air on the leeward side is known as a rain shadow.

World Climate Patterns Chapter 3, Section 3

For use with textbook pages 65–69.

Terms to Know

natural vegetation The plant life that grows in an area where the natural environment has not been changed by human activity (page 66) coniferous A type of tree with cones and needle-shaped leaves (page 68)

oasis An area of lush vegetation in the desert (page 67)

deciduous A type of tree with broad leaves that drop in autumn (page 65)

mixed forest A forest with both deciduous and coniferous trees (page 68)

chaparral Thickets of woody bushes and short trees (page 68)

prairie Inland grasslands (page 68) permafrost The frozen subsoil (page 68) hypothesis Scientific explanation (page 69)

smog A visible chemical haze that endangers people’s health (page 69)

Major Climates and Vegetation

Introduction (page 65) Ordinary climate patterns can be different from region to region, depending on the climate factors present.

Climate Regions (page 65) Geographers divide the earth into several climate regions. Each region has its own type of soil and natural vegetation, or plant life growing in an area that has not been changed by human activity. There are five major climate regions:

A. Tropical climates are found in or near the low latitudes.

1.  A tropical rain forest climate is hot and humid. It rains almost

everyday.  The vegetation grows thickly in layers.  Tall trees form a canopy over shorter trees and bushes.  Vines and shade-tolerant plants grow on the rain forest floor.

2.  A Tropical Savanna climate has dry winters and wet summers, with hot temperatures year-round. Fewer trees grow here than in rain forests. Coarse grass covers the ground.

B.  Dry climates are areas with little precipitation and temperatures that vary from hot during the day to cool at night.  There are two types of dry climates. 1.)       The desert climate has little vegetation, with some scrub and cactus. Some desert areas have underground springs to support an oasis. This is an area with abundant vegetation. 2.)     Steppe climate regions have grasslands with few trees.

C.  Mid-latitude climates include four temperate climate regions.

1.  Marine west coast climates have ocean winds that bring cool summers and damp winters.  Vegetation consists of coniferous and deciduous trees. Deciduous trees have wide leaves that change color and drop in autumn. Coniferous trees have cones and needle-like leaves. Marine west coast climates have mixed forests with both evergreen and deciduous trees.

2.  A Mediterranean climate is found near the Mediterranean Sea, in southern California, and in parts of southern Australia. Mediterranean climates have mild, rainy winters and hot, sunny summers.  The vegetation includes chaparral, which are woody bushes and short trees.

3.  Humid sub-tropical climates in the southeastern United States, South America, and Asia have short, mild winters and nearly year- round rain.  Vegetation includes mixed forests and inland grass- lands called prairies.

4.  A humid continental climate is found in the northern United States, southern Canada, Eastern Europe, and northeastern China. The further north in this climate, the longer and more severe are the snowy winters and the shorter and cooler are the summers. The vegetation is a mixture of deciduous and evergreen trees.

D. High latitude climates have freezing temperatures most of the year. There is little vegetation in the three high latitude climate regions.

1.  The subarctic is just south of the Arctic Circle.  Winters are long and very cold. Summers are short and cool. In many parts of the subarctic, only a thin layer of the surface soil thaws each summer. The permanently frozen subsoil below it is called permafrost. The vegetation is mostly coniferous evergreens.

2.  The tundra climates are closer to Polar regions and colder than subarctic.  Winter is dark and bitterly cold.  The constant sunlight in summer brings little heat.  The vegetation is limited to low bushes, short grasses, moss, and lichens.

3.  The ice cap climates are located in Antarctica and the interior of Greenland, where the temperature averages below freezing.  The surface in this region is always covered with snow and ice. Lichens are the only vegetation.

E.  High mountains, or highlands climates, are similar to high latitude climates because of the thinning atmosphere at high altitudes.  The higher the elevation, the cooler the temperature. Mixed forests are found at the base of mountain ranges. Higher up, meadows with small trees, shrubs, and wildflowers are on mountainsides.

Climate Changes (page 69) Climates change over time. For example, the earth has experienced four eras, known as ice ages, when glaciers covered large areas of the planet’s surface. These eras occurred during the last 1 to 2 million years. One hypothesis, or scientific explanation, for the ice ages is that the earth soaked up less solar energy because of changes in the earth’s orbit. Another hypothesis is that dust clouds from volcanic activity reflected sunlight back into space, cooling the atmosphere and lowering surface temperatures.

Human interaction with the environment also affects climate. The burning of fossil fuels releases gases that mix with water in the air. This forms acid that could destroy forests when it falls in rain and snow. The exhaust released from fossil fuels can also form smog. Smog is a visible chemical haze in the atmosphere that endangers people’s health. Building dams and changing the flow of rivers may cause areas of land to flood or dry out. These changes all will affect climate over time.