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Name _____________________________ Class _________________ Date __________________ Physical Geography: Climate and Vegetation Section 2 Climate Terms and Names convection the transfer of heat in the atmosphere by upward motion of the air El Niño the warming of waters off the west coast of South America greenhouse effect the theory that gases released by burning coal and petroleum trap solar energy, causing higher temperatures Before You Read In the last section, you learned how the earth’s rotation creates weather and seasons. In this section, you will read about the factors that create and change climate. As You Read Use a chart to take notes on factors that affect climate. Factors Affecting Climate a coastal region chill the air. Sometimes they prevent warm air and the moisture it holds from falling to earth. WIND CURRENTS/OCEAN CURRENTS (Pages 54–55) What is convection? 1. How do wind and ocean currents affect the climate? Wind and ocean currents help distribute the sun’s heat from one part of the world to another. This is done through convection. Convection is the transfer of heat in the atmosphere by upward motion of the air. Convection occurs when the sunlight heats the atmosphere. The heated air expands. A region of low air pressure is created by this expansion. Cooler denser air in a nearby high-pressure region rushes into the low-pressure area. Ocean currents are like rivers flowing in the ocean. Warm water flows away from the equator toward the poles, and cold water flows back toward the equator. Winds blowing over the ocean currents are heated or cooled by the currents. The winds then affect the lands that the winds blow across. Currents also affect the precipitation in an area. Cold ocean currents flowing along _______________________________ _______________________________ ZONES OF LATITUDE (Pages 55–56) How does latitude location affect climate? Geographers divide the earth into three general regions of latitude: low or tropical, middle or temperate, and high or polar. Tropical regions are found on either side of the equator. Lands in tropical regions are hot all year long. In some areas, a shift in wind patterns causes variations in climate. The high latitude or polar regions circle the North Pole and South Pole. They are cold all year. During summer in the polar regions, the temperature reaches a high of only 50° F. © Houghton Mifflin Harcourt Publishing Company 31 Guided Reading Workbook Name _____________________________ Class _________________ Date __________________ Section 2, continued An example of a natural change is El Niño. This is warming of the waters off the west coast of South America. About every two to seven years, the eastern winds that blow over the central Pacific Ocean slow or reverse direction. This changes the ocean temperature and affects the weather worldwide. Usually, these easterly winds bring seasonal rains and push warm ocean water toward Asia and Australia. In El Niño years, however, the winds push warm water and heavy rains toward the Americas. This can cause floods and mudslides there. At the same time Australia and Asia experience drought conditions. When the winds blow in the opposite direction, to the west, the warmer waters are pushed to the lands on the western Pacific rim. This is called La Niña. La Niña causes increased precipitation in places such as India and increased dryness on the eastern side of the Pacific. The earth’s two temperate regions lie at the middle latitudes. They are between the tropics and the polar regions. Within the temperate regions, climates can vary greatly. The variations range from relatively hot to relatively cold. These variations occur because solar heating is greater in the summer than in the winter. 2. What are the three general regions of latitude? ______________________________ ______________________________ ELEVATION/TOPOGRAPHY (Page 56) How does elevation affect climate? Another factor in determining a region’s climate is elevation, or distance above sea level. The air temperature drops as elevation increases. Climates above 12,000 feet become like those in Arctic areas. Landforms also affect climate. This is especially true of mountain areas. Remember that as winds move up the side of a mountain they cool. They also lose their ability to hold moisture and release rain or snow. By the time the winds reach the other side of the mountain, they are dry and become warmer as they flow down the mountain. 4. What happens in the Americas during El Niño? _______________________________ _______________________________ GLOBAL CLIMATE CHANGE (Page 58) What is global warming? 3. What happens to winds as they move up the side of a mountain? Evidence shows that climates are changing around the world. Since the late 1800s, the temperature of the earth has increased by one degree Fahrenheit. Estimates suggest that temperature will increase from 3.2 to 7.2 degrees in the next century. Some argue that this warming is part of the earth's natural cycle. However, most climate scientists argue that global temperature increases are caused by the greenhouse effect. The ______________________________ ______________________________ Changes in Climate EL NIÑO (Pages 56–57) How does El Niño affect the weather? Climates change over time. Changes in climate are natural and the result of human activities. © Houghton Mifflin Harcourt Publishing Company 32 Guided Reading Workbook Name _____________________________ Class _________________ Date __________________ Section 2, continued greenhouse effect occurs when the layer of gases released by the burning of coal and petroleum traps solar energy. This causes higher temperatures in the same way that a greenhouse traps solar energy. The greenhouse effect and global warming will probably increase as more nations industrialize. If this trend continues, ice caps will melt, flooding some coastal areas and covering some islands. Weather patterns could also become more erratic. 5. What are some of the predicted results of the greenhouse effect? _______________________________ _______________________________ © Houghton Mifflin Harcourt Publishing Company 33 Guided Reading Workbook Name _____________________________ Class _________________ Date __________________ Section 2, continued Use the chart below to take notes on how each of the following affects climate. Factors Affecting Climate 1. wind currents 2. ocean currents 3. zones of latitude 4. altitude 5. topography © Houghton Mifflin Harcourt Publishing Company 34 Guided Reading Workbook