Transcript wgt_ch03
World Geography Today Chapter 3 Weather and Climate Preview Section 1: Factors Affecting Climate Section 2: Weather Factors Section 3: Climate and Vegetation Patterns Chapter Wrap-Up World Geography Today Chapter 3 Section 1: Factors Affecting Climate Read to Discover • How does the Sun affect Earth’s atmosphere? • How does atmospheric pressure distribute energy around the globe? • How do global wind belts affect weather and climate? • How do the oceans affect weather and climate? World Geography Today Chapter 3 Section 1: Factors Affecting Climate Question By which processes does the Sun interact with Earth’s atmosphere? World Geography Today Chapter 3 Section 1: Factors Affecting Climate The Sun’s Effect on Earth The Sun’s energy reaches Earth. The other half is absorbed by Earth’s surface and converted into heat energy. Half of the energy is reflected back into space or absorbed by the atmosphere. The greenhouse effect helps keep the planet warm. The atmosphere traps this heat in a process called the greenhouse effect. World Geography Today Chapter 3 Section 1: Factors Affecting Climate Atmospheric Pressure • Low-pressure zones are caused by warm air, which expands and rises. • High-pressure zones are caused by cold air, which is dense and sinks. • Pressure differences cause airflow and energy distribution around the globe. • Warm air moves through the upper atmosphere until the air cools and falls; cold air sinks toward Earth’s surface and then heats up and rises. World Geography Today Chapter 3 Section 1: Factors Affecting Climate Global Winds • Pressure differences cause wind. • Winds move heat and cold across Earth’s surface. • Prevailing winds blow from the same direction most of the time, causing similar weather. • A front occurs when two air masses of widely different temperatures or moisture levels meet. World Geography Today Chapter 3 Section 1: Factors Affecting Climate Oceans • Water heats and cools more slowly than land, making coastal areas milder than inland areas. • Ocean currents move heat between the tropics and polar regions, helping to maintain Earth’s energy balance. World Geography Today Chapter 3 Section 2: Weather Factors Read to Discover • What are the common forms of precipitation, and how are they formed? • How do mountains and elevation affect weather and climate? • What are the different types of storms, and how do they form? World Geography Today Chapter 3 Section 2: Weather Factors Question What are the steps in the formation of precipitation, and what are the four common types of precipitation? World Geography Today Chapter 3 Section 2: Weather Factors Formation of Precipitation Evaporation Rain Humidity Snow Condensation clouds, dew, fog, frost Sleet Hail World Geography Today Chapter 3 Section 2: Weather Factors Forms of Precipitation • Rain—Liquid formed through condensation of water vapor • Snow—Ice crystals formed in clouds • Sleet—Rain that freezes as it falls • Hail—Chunks of ice formed in storm clouds World Geography Today Chapter 3 Section 2: Weather Factors Question How do mountains and elevation affect weather and climate? World Geography Today Chapter 3 Section 2: Weather Factors • Increase in elevation causes drop in temperature. • Mountains cause orographic effect: Moist air meets a barrier and is pushed upward, causing cooling, condensation, and precipitation. • Mountainside facing wind is the windward, wetter side; side facing away from wind is the leeward, drier side, called the rain shadow. World Geography Today Chapter 3 Section 2: Weather Factors Types of Storms • Middle-latitude storms form when cold, dry polar air mixes with moist, warm tropical air. Examples include thunderstorms and tornadoes. • Tropical storms are usually smaller and lack fronts. Examples include hurricanes and typhoons. World Geography Today Chapter 3 Section 3: Climate and Vegetation Patterns Read to Discover • How do the two tropical climates differ? • What conditions are common in dry climates? • What climates are found in the middle latitudes? • What characterizes high-latitude and highland climates? World Geography Today Chapter 3 Section 3: Climate and Vegetation Patterns Question What are the characteristics of tropical humid and tropical wet and dry climates? World Geography Today Chapter 3 Section 3: Climate and Vegetation Patterns Tropical Humid Climate • Close to equator • Warm temperatures • Rainfall all year • Receives Sun’s rays directly all year • Rising warm air • Rain forests • Monsoons Tropical Wet and Dry Climates • North and south of tropical humid • Caused by seasonal change in this area • Alternating wet and dry seasons • Savannas World Geography Today Chapter 3 Section 3: Climate and Vegetation Patterns Dry Climate Areas • Generally centered about 30 degrees north and south of equator • Subtropical high-pressure zone causes sinking dry air, with little rain. • Winters may be very cold, summers very hot. • Hardy plants and animals World Geography Today Chapter 3 Section 3: Climate and Vegetation Patterns Middle-Latitude Climates • Mediterranean—Long, dry summers and mild winters; scrub woodland vegetation • Humid Subtropical—Hot, humid summers and mild winters; temperate forests • Marine West Coast—Mild all year; may support dense forests • Humid Continental—Variable, with four seasons; enough rain to support forests World Geography Today Chapter 3 Section 3: Climate and Vegetation Patterns High-Latitude and Highland Climates • Subarctic—Long, cold winters and short, warm summers; vast evergreen forests • Tundra—Long winters, with permafrost; low shrubs, lichens, mosses, ferns • Ice Cap—Polar climates; few land plants or animals • Highland—Varies by elevation, with low elevations relatively mild and high elevations similar to ice cap World Geography Today Chapter 3 Chapter Wrap-Up Understanding the Main Ideas 1. How does latitude relate to climate? 2. How do atmospheric pressure zones and ocean currents affect Earth’s energy balance? 3. On a global scale, where is precipitation most common? 4. What effects can hurricanes have on local environments? 5. Where will you find climates that are generally warm and wet all year? What creates dry weather conditions in arid regions?