Weather and Climate

1. CHAPTER 3 Weather and Climate Section 1: Factors Affecting Climate Section 2: Weather Factors Section 3: Climate and Vegetation Patterns

2. Section 1Factors Affecting Climate Objectives: • 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?

3. Section 1Factors Affecting Climate Effect of the Sun on Earth’s atmosphere: • Some solar energy, in the form of heat, reflects off Earth back into the atmosphere. • Atmosphere traps this heat energy in a process called the greenhouse effect. • Process helps keep the planet warm.

4. Section 1Factors Affecting Climate Atmospheric pressure and energy distribution: • 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 air flow and energy distribution around the globe. • Warm air moves through the upper atmosphere until it cools and falls; cold air moves along Earth’s surface until it heats up and rises.

5. Section 1Factors Affecting Climate Global winds affect weather and climate: • Pressure differences cause wind. • Winds move heat and cold across the 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.

6. Section 1Factors Affecting Climate Oceans affect weather and climate: • 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.

7. Section 2Weather Factors Objectives: • 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?

8. Section 2Weather 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

9. Section 2Weather Factors Effects of mountains and elevation on weather and climate: • 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.

10. Section 2Weather 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.

11. Section 3Climate andVegetation Patterns Objectives: • 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?

12. Section 3Climate andVegetation Patterns Differences in the two tropical climates: • Tropical humid climate • close to equator • generally warm and wet year-round • climate supports dense rain forests • Tropical wet and dry climate • farther from equator; north and south of the tropical humid zone • warm wet season alternates with cooler, drier season • seasonal variation supports savannas: tropical grasslands with scattered trees and shrubs

13. Section 3Climate andVegetation 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 cold, summers very hot • hardy plants and animals

14. Section 3Climate andVegetation 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 year-round; may support dense forests • humid continental—variable, with four seasons; enough rain to support forests

15. Section 3Climate andVegetation Patterns High-latitude and highland climates: • subarctic—long cold winters and short warm summers; vast evergreen forests • tundra—long winters, with permafrost; low vegetation • ice cap—polar climates, with few plants or land animals • highland—climate varies by elevation, with low elevations relatively mild and high elevations similar to ice cap