Weather and Climate Main Ideas The Big Idea The sun, location, wind, water, and mountains affect weather and climate. Main Ideas While weather is short term, climate is a region’s average weather over a long period. The amount of sun at a given location is affected by Earth’s tilt, movement, and shape. Wind and water move heat around Earth, affecting how warm or wet a place is. Mountains influence temperature and precipitation.
Main Idea 1: While weather is short term, climate is a region’s average weather over a long period. The short-term changes in the air for a given place and time Temperature and precipitation from hour to hour or day to day Climate A region’s average weather conditions over a long period The expected weather for a place based on data and experience
Main Idea 2: The amount of sun at a given location is affected by Earth’s tilt, movement, and shape. The part of the Earth tilted toward the sun receives more solar energy than the part tilted away from the sun. Movement As Earth revolves around the sun, the part of Earth that is tilted toward the sun changes during the year, thus creating the seasons. Shape Earth’s spherical shape means that the sun’s rays directly strike the equator, but only somewhat strike the poles. The farther from the equator, or the higher the latitude, the colder the climate.
Main Idea 3: Wind and water move heat around Earth, affecting how warm or wet a place is. Air and water warmed by the sun are constantly on the move, making different areas of Earth warmer or cooler. Wind, or the sideways movement of air, blows in great streams around the planet. Prevailing winds are winds that blow in the same direction over large areas of Earth
Wind Weight of air Cold air is heavier than warm air. When air cools, it gets heavier and sinks. When air warms, it gets lighter and rises. As warm air rises, cooler air moves in to take its place, creating wind. The rising, sinking, and flowing of air creates Earth’s prevailing wind patterns. At the equator, hot air rises and flows toward the poles. At the poles, cold air sinks and flows toward the equator. Earth’s rotation causes prevailing winds to curve east or west. Prevailing winds can make a region warmer or colder and drier or wetter.
Water and Wind Ocean currents—large streams of surface seawater driven by winds—move heat around Earth. Carry warm or cool water to different areas Water’s temperature affects air temperature near it. Large bodies of water, such as an ocean or sea, also affect climate. Water heats and cools more slowly than land does. Large bodies of water make the temperature of the land nearby milder. The place where two air masses of different temperatures or moisture content meet is a front. Can produce rain, snow, thunderstorms, and blizzards
Storms Thunderstorms Blizzards Tornadoes Produce rain, lightning, and thunder Most common in spring and summer Blizzards Produce strong winds and large amounts of snow Most common during winter Tornadoes Small, rapidly twisting funnel of air that touches the ground Can be destructive and deadly Hurricanes and Typhoons Large, rotating storms that form over tropical waters in the Atlantic Ocean (hurricanes) or Pacific Ocean (typhoons). Produce drenching rains, strong winds, and storm surges Largest, most destructive storms
Main Idea 4: Mountains influence temperature and precipitation. Mountains can influence an area’s climate by affecting both temperature and precipitation. Temperature decreases with elevation, the height on Earth’s surface above sea level. Mountains also create wet and dry areas. Air blowing against mountains is forced to rise. As the air rises, it cools and precipitation falls. This effect produces a rain shadow, a dry area on the mountainside facing away from the direction of the wind.
World Climates The Big Idea Earth’s five major climate zones are identified by temperature, precipitation, and plant life. Main Ideas Geographers use temperature, precipitation, and plant life to identify climate zones. Tropical climates are wet and warm, while dry climates receive little or no rain. Temperate climates have the most seasonal change. Polar climates are cold and dry, while highland climates change with elevation.
Main Idea 1: Geographers use temperature, precipitation, and plant life to identify climate zones. Earth is divided into five general climate zones. Tropical—occur near the equator, in low latitudes Temperate—occur about halfway between the equator and the poles, in the middle latitudes Polar—occur near the poles, in the high latitudes Dry—occurs at many different latitudes Highland—occurs at many different latitudes Geographers divide some climate zones into more specific climate regions.
Main Idea 2: Tropical climates are wet and warm, while dry climates receive little or no rain. Humid Tropical Climate At the equator Warm, muggy and rainy year-round Temperatures average 80F. Rainfall ranges from 70 to 450 inches. Some areas have monsoons, seasonal winds that bring either dry or moist air. Can support lush tropical rain forests that host a great diversity of plant and animal life Tropical Savanna Climate North and south away from the equator Long, hot, dry season followed by short periods of rain Temperatures are hot in the summer, cooler in the winter. Can support savannas—areas of tall grasses and scattered trees and shrubs
Dry Climates Desert Climate Steppe Climate Earth’s hottest and driest climate Receive less than 10 inches of rain a year Temperatures can reach as high as 130F. Only very hardy plants and animals can live in these conditions. Steppe Climate Semidry grasslands or prairies—called steppes Often border deserts Receive slightly more rain than deserts Short grasses are most common plants, but shrubs and trees grow along streams and rivers.
Main Idea 3: Temperate climates have the most seasonal change. Mild and tend to have four seasons Warm or hot summers Cool or cold winters Occur in the middle latitudes, the regions halfway between the equator and the poles
Temperate Climates Mediterranean Humid Subtropical Marine West Coast Sunny, pleasant climate occurring mainly in coastal areas Summers hot, dry, and sunny; winters mild and somewhat wet Humid Subtropical Occurs along east coasts near the tropics Summers are hot and muggy; winters are mild Storms occur year-round. Marine West Coast Occurs on west coasts where winds carry moisture in from the seas Mild temperatures year-round Humid Continental Occurs closer to the poles, in the upper-middle latitudes Four distinct seasons Next
Main Idea 4: Polar climates are cold and dry, while highland climates change with elevation. Subarctic Climate Occurs mainly in Northern hemisphere south of Arctic Ocean Winters are long and bitterly cold; summers short and cool Below freezing half the year Tundra Climate Coastal areas along the Arctic Ocean Long, bitterly cold winters In some parts is permafrost, or permanently frozen layers of soil Ice Cap Climate North and South poles Temperature lows of more than -120F Snow and ice remain year-round, but little precipitation Highland Climate Found on mountains Includes polar climates plus others; several climates in one As you go up a mountain, temperatures drop and plant life grows sparser. Next
Natural Environments Main Ideas The Big Idea Plants, animals, and the environment, including soil, interact and affect one another. Main Ideas The environment and life are interconnected and exist in a fragile balance. Soils play an important role in the environment.
Main Idea 1: The environment and life are interconnected and exist in a fragile balance. Plants and animals live where they are suited to the environment, or surroundings. Factors such as temperature, rainfall, and soil conditions limit options of where they can live. All plants and animals are adapted to specific environments. Ecosystem—a group of plants and animals that depend on each other for survival and the environment in which they live Formed from interconnections between living things and the environment Can be any size and can occur wherever air, water, and soil support life
Changes to Environment Ecosystems exist in a fragile balance; a small change to one part can affect the whole system. People can affect ecosystems in many ways. Some actions can destroy a habitat—the place where a plant or animal lives. Extreme changes in ecosystems can cause species to die out, or become extinct. Many countries are working to balance people’s needs with the needs of the environment.
Main Idea 2: Soils play an important role in the environment. Soils help determine what plants will grow and how well. Fertile soils are rich in minerals and humus, decayed plant or animal matter. Support abundant life Soils can lose fertility in many ways. Erosion Planting the same crops over and over When soil becomes worn out, it cannot support as many plants. Can lead to desertification, the spread of desertlike conditions
Natural Resources Main Ideas The Big Idea The sun, location, wind, water, and mountains affect weather and climate. Main Ideas Earth provides valuable resources for our use. Energy resources provide fuel, heat, and electricity. Mineral resources include metals, rocks, and salt. Resources shape people’s lives and countries’ wealth.
Main Idea 1: Earth provides valuable resources for our use. Using Natural Resources A natural resource is any material in nature that people use and value. Some are used as is. Some are changed to make something new Types of Natural Resources Renewable resources are resources Earth replaces naturally. Nonrenewable resources are resources that cannot be replaced; they will run out one day. Managing Natural Resources People must manage resources to ensure they will be available in the future. Deforestation, the clearing of trees, is a result of lack of management. Reforestation, planting trees to replace lost forestland, works to prevent resource loss.
Main Idea 2: Energy resources provide fuel, heat, and electricity. Nonrenewable Energy Resources Most energy we use comes from fossil fuels, nonrenewable resources that formed from the remains of ancient plants and animals. Coal—pollutes the air; used mainly to create electricity at power plants Petroleum, or oil—used to make fuels and other products Natural gas—cleanest-burning fossil fuel; used mainly for heating and cooking Renewable Energy Resources Will not run out Generally better for the environment Hydroelectric power—the production of electricity from waterpower—is the main alternative to fossil fuels. Wind is used to power wind turbines that create electricity. Solar power and geothermal energy—heat from within Earth—can heat water for homes and be turned into electricity
Nuclear Energy Obtained by splitting atoms, small particles of matter Uses the metal uranium, so some consider it a nonrenewable resource Produces dangerous wastes that must be stored for thousands of years before they are safe Accidents at nuclear power plants have terrible effects.
Main Idea 3: Mineral resources include metals, rocks, and salt. Mineral resources include metals, salt, rocks, and gemstones. Minerals fulfill countless needs. Minerals are nonrenewable, and therefore need to be conserved. Recycling can make the supply of mineral resources last longer.
Main Idea 4: Resources shape people’s lives and countries’ wealth. The natural resources available to people affect their lifestyles and needs. People in areas with many natural resources sometimes have more choices on ways to dress, eat, live, travel, and entertain themselves. People in areas with fewer natural resources will likely have fewer choices and different needs. Availability of natural resources affects countries’ economies. The many resources available in the United States have helped it become one of the world’s wealthiest economies. Countries with few natural resources often have weak economies. Some countries have only one or two valuable resources but few others.
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