Download Geography Chapter 2 Notes

Geography Chapter 2 Notes
The Water Cycle
 Seventy percent of the earth’s surface is covered with water. 
 There is water literally all around us in the form of water vapor, or water in the
atmosphere in the form of gas. 
 Although the amount of water does not change, its form does. 
 Water in oceans goes to the air, then to the ground, and finally returns to the oceans.
 This is known as the water cycle. 
 The sun’s heat turns liquid water into water vapor, or humidity. 
 This process is known as evaporation. 
 As water vapor rises and cools, it changes back into liquid in a process called
condensation.
 Tiny droplets of water form clouds and fall back to the earth in the from of
precipitation—rain, snow, sleet, or hail. 
 Precipitation soaks into the ground and collects in stream and rivers. 
 During collection, streams and rivers carry the water back to the oceans.
Water Resources
• Only about 2 percent of the water found on the earth is freshwater. 
• Of that 2 percent, about 1.6 percent is frozen into giant sheets of ice, or glaciers.
• Groundwater fills tiny cracks and holes in the rock layers below the earth’s surface. 
• There is 10 times more groundwater than there is water in rivers and lakes.
• Some of this water flows through underground rock layers called aquifers. 
• The earth’s four major oceans—the Pacific, Atlantic, Indian, and Arctic Oceans—contain
salt water, which is not fit for human consumption.
Section 2
Weather and Climate
• Weather refers to the unpredictable changes in air that take place over a short period of
time. 
• Climate is the usual, predictable pattern of weather in an area over a long period of time.
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• Climate is affected by the sun, the wind, the oceans and other bodies of water, landforms,
and even people. 
• To understand an area’s climate, scientists look at extremes of temperature and
precipitation.
The Sun and Climate
• The original source of climate is the sun. 
• Wind and water carry the sun’s heat around the globe. 
• A place’s climate is also affected by its latitude. 
• The sun’s rays hit the earth more directly at low latitudes. 
• Places at higher latitudes receive only angled rays of the sun.
• The areas near the Equator are known as the Tropics. 
• They lie between the Tropic of Cancer (23½°N latitude) and the Tropic of Capricorn
(23½°S latitude). 
• The Tropics experience a hot climate year-round.
The Wind’s Effect on Climate
• Movements of air are called winds. 
• Winds follow typical patterns, affecting climate. 
Monsoons are powerful seasonal winds that blow over continents for months at a time. 
They are found mainly in Asia and some areas in Africa.
Thunderstorms sometimes produce tornadoes, or funnel-shaped windstorms. 
Although they occur all over the world, the United States experiences more tornadoes
than any other area. 
• Violent tropical storms called hurricanes form over the warm waters of the Atlantic
Ocean in the late summer and early fall.
• Hurricanes usually strike the Caribbean islands and North America. 
• When the same type of storm hits Asia, it is called a typhoon. 
• A long period of extended dryness is called a drought. 
• El Niño—a unique combination of temperature, wind, and water effects in the Pacific
Ocean—last occurred in 2004.
• El Niños occur about every three years and form when cold winds from the east are weak
and the Pacific Ocean gets warmer than usual.
• When the opposite kind of unusual weather takes place, the event is known as La Niña.
Ocean Currents
• Moving streams of water called currents carry warm or cool water through the world’s
oceans. 
• These currents affect the climate of land areas. 
• Winds that blow over warm currents, for example, carry warm air to land areas.
Landforms and Climate
• The shape of land and the location of landforms in relation to one another and to water
also affect climate. 
• Local winds are patterns of wind caused by landforms in a particular area. 
• Some local winds occur because land warms and cools more quickly than water.
• As a result, cool sea breezes keep coastal areas cool during the day. 
• After the sun sets, the land cools down, and cool breezes blow out to sea. 
• The higher the elevation a place has, the cooler it will be. 
• As air moves up the windward side of mountain peaks, it becomes cool and loses its
moisture.
• The air that crosses over the peaks is dry, creating a rain shadow. 
• A rain shadow is a dry area on the leeward side of the mountains. 
• The dry air of a rain shadow warms up again as it moves down mountainsides, giving the
region a dry or desert climate.
The Impact of People on Climate
• People’s actions affect climate. 
• For example, cities are warmer than rural areas because streets and buildings absorb more
heat than plants and trees do. 
• In addition, people burn fuels, which raises temperatures. 
• In the past 200 years, people have burned coal, oil, and natural gas as sources of energy.
• The buildup of the gases from the burning of these substances has prevented warm air
from rising and escaping into the atmosphere. 
• This is known as the greenhouse effect, in which the earth’s temperature will increase. 
• Dense forests that receive high amounts of rain each year are known as rain forests.
• People burn trees to clear rain forests, which leads to the greenhouse effect. 
• Also, less water evaporates if there are fewer trees, decreasing rainfall.
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Section 3
Tropical Climates
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There are two types of tropical climates—tropical rain forest and tropical savanna.
Areas with a tropical rain forest climate have year-round rains that produce lush
vegetation and thick rain forests. 
• Tall hardwood trees such as mahogany, teak, and ebony form a canopy, or top layer of
the forest.
• Tropical savanna areas have a definite wet season, while the remainder of the year is hot
and dry. 
• Savannas, or broad grasslands with few trees, are found in these areas.
Mid-Latitude Climates
• Mid-latitude climates include more and different climate zones. 
• This is due to a mix of air masses: warm air from the Tropics and cool air from the Polar
Regions. 
• The marine west coast climate occurs along coastal areas that receive winds from the
ocean.
• Winters are rainy and summers are cool in these areas. 
• Deciduous and coniferous trees grow in this climate. 
• The coastal Mediterranean climate also has rainy, mild winters. 
• It differs from the marine west coast climate in that the Mediterranean climate
experiences hot, dry summers.
• Shrubs and short trees grow in this climate. 
• The humid continental climate occurs in the inland areas of North America, Europe,
and Asia. 
• Winters can be long, cold, and snowy. 
• Summers are short and may be very hot.
• Deciduous trees and vast grasslands grow here. 
• Mid-latitude regions close to the Tropics experience a humid subtropical climate where
rain falls throughout the year. 
• Oak, magnolia, and palm trees grow here.
High Latitude Climates
• In the high latitudes nearest the mid-latitude zones, you will find the subarctic climate. 
• Winters are severely cold and bitter. 
• Huge evergreens forests called taiga grow here. 
• Closer to the Poles than the subarctic zone lie areas of vast rolling plains without trees.
• This region is known as the tundra and is harsh and dry. 
• In these parts, much of the lower layers of soil stay permanently frozen and are known as
permafrost. 
• Only sturdy grasses and low berry bushes grow here. 
• The ice cap climate is found at the Poles and on the ice sheets of Antarctica and
Greenland.
• No vegetation grows here. 
• Only lichens can live on the rocks.
Dry Climates
• Desert climates—the driest climates—have less than 10 inches of rainfall a year.
• Only scattered plants like cacti can live here. 
• Many deserts are surrounded by partly dry grasslands known as steppes. 
• The Great Plains of the United States has a steppe climate, that averages 10 to 20 inches
of rain a year.
Highland Climate
• Mountains tend to have cool climates—even near the Equator. 
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A highland, or mountain, climate has cool or cold temperatures throughout the year. 
No trees grow above the timberline.
Section 4
The Atmosphere
• The atmosphere is the blanket of gases, or air, surrounding the earth. 
• Air pollution consists of fumes and chemicals from vehicles and industries. 
• It also includes solid particles such as ash and dust. 
• Global effects of air pollution include global warming, ozone depletion, and acid rain.
• The ozone layer, which filters out harmful sun rays, is being depleted by chemicals in air
pollution. 
• When chemicals in air pollution combine with precipitation, they can create acid rain,
which kills fish and forests.
The Lithosphere
• The lithosphere is the earth’s hard outer shell, or what we call the land areas. 
• The lithosphere can be damaged by mining for minerals and ores such as copper and iron.

• If not properly managed, rich topsoil can be carried away by wind and water.
• Deforestation, or cutting down forests without replanting, can cause topsoil to be lost. 
• Farmers can enrich topsoil by using fertilizers and practicing crop rotation, which
involves changing what is planted in a field.
The Hydrosphere
• The hydrosphere includes all the water in the oceans, lakes, rivers, glaciers, and so forth,
plus precipitation. 
• Because people, plants, and most animals require freshwater, it is important that it be
carefully managed. 
• Conservation is an important part of water management and involves not wasting water.

• Another part of water management involves avoiding polluting water.
• In irrigation, water is collected and distributed to crops. 
• As much as 70 percent of all water is used for farming, and most irrigation methods are
wasteful. 
• Some industrial processes result in dangerous chemicals entering the water supply. 
• Pesticides, or powerful chemicals that kill crop-destroying insects, can seep into water
and pollute it.
The Biosphere
• The biosphere includes all living things along with the environments in which they live.

• As humans expand their communities, they invade ecosystems, or places where plants
and animals are dependent on one another and their surroundings. 
• Changes that humans make, such as draining wetlands, can destroy the balance of
ecosystems.
• People are learning the importance of protecting ecosystems. 
• Sometimes the need to protect the environment clashes with people’s survival needs,
requiring that new ways be found to meet these needs.
Section 1: The Water Planet Main Idea
Water is one of the earth’s most precious resources. 
• Region Water covers about 70 percent of the earth’s surface. 
•
Movement Water follows a cycle of evaporation, condensation, precipitation, and
collection on and beneath the ground. 
• Science Humans and most animals need freshwater to live. Only a small fraction of the
world’s water is found in rivers and lakes.
Section 2: Climate Main Idea
Wind and water carry rainfall and the sun’s warmth around the world to create different climates.

• Region Climate is the usual pattern of weather over a long period of time. 
• Region The Tropics, near the Equator, receive more of the sun’s warmth than other
regions. 
• Location Landforms and position near water affect climate in a local area. 
• Culture Human actions like building cities, burning fuels, and clearing the rain forests
can affect climate.
Section 3: Climate Zones and Vegetation Main Idea
Geographers divide the world into different climate zones. 
• Region The world has five main climate regions that are based on latitude, amount of
moisture, and/or elevation. These regions are tropical, mid-latitude, high latitude, dry,
and highland. 
• Region Each climate zone has particular kinds of vegetation
Section 4: An Environmental Balance Main Idea
People’s actions affect the environment. 
• Human/Environment Interaction A delicate balance exists among the earth’s
hydrosphere, lithosphere, atmosphere, and biosphere. 
• Human/Environment Interaction People need to carefully manage and conserve water
and land resources.