Lesson Outline LESSON 2 A. Long-Term Cycles 1. A(n) climate cycle takes much longer than a lifetime to complete. a. To learn about long-term climate cycles, scientists study natural records, such as growth rings of trees, fossilized pollen, and ocean. b. Scientists use this information to compare climates to ancient climates. 2. Long-term cold periods when glaciers cover most of Earth are called. a. The most recent ice age began about years ago. b. The maximum size of the ice sheets was reached years ago. c. are the warm periods that occur during ice ages. d. The current interglacial period is the Epoch. 3. The shape of Earth s affects climate changes. a. Earth is cooler if the shape of its orbit is, because Earth is then farther from the Sun. b. Changes in the of Earth s tilt also affect climate. B. Short-Term Cycles 1. Seasonal are one source of short-term climate cycles. a. Seasons are caused by the of Earth s axis. b. Changes in tilt change the amount of received in different regions throughout a year. c. When the northern hemisphere is tilted toward the Sun, it is in the northern hemisphere. d. On the summer, which occurs on June 21 or 22 in the northern hemisphere, Earth s axis is tilted toward the Sun. e. The solstice in the northern hemisphere begins on December 21 or 22, at which time Earth s axis is tilted away from the Sun. f. On a(n), northern and southern hemispheres receive equal amounts of sunlight. Climate 29
Lesson Outline continued 2. In the Ocean, trade winds usually blow from east to west. a. When these winds blow warm water away from South America, cold water rushes upward in the ocean in a process called. b. Air over warm, eastern Pacific water has a(n) air pressure compared to the air over colder water, keeping the wind blowing from east to west. 3. occurs when the trade winds weaken and air pressure patterns are reversed, resulting in climate changes on Earth. 4. The combined ocean and atmospheric cycle that results in weakened trade winds across the Pacific Ocean is called. 5. The changes climate for years by changing the position of the jet stream. 6. A wind circulation pattern that changes direction with the seasons is called a(n). a. Monsoons are the result of temperature differences between the and the land. b. When winds blow from high pressure over the to low pressure over C. Droughts, Heat Waves, and Cold Waves, they bring heavy rains. 1. During a(n), an area has less precipitation than usual. 2. Droughts are often accompanied by, which are periods of unusually high temperatures. 3. Long periods of unusually cold temperature are called. 30 Climate
Content Practice A LESSON 2 Climate Cycle Directions: On each line, write the term from the word bank that correctly completes each sentence. Each term is used only once. axis climate drought El Niño/Southern Oscillation heat wave ice ages interglacials monsoon ocean orbit seasons 1. Cold periods lasting from hundreds to millions of years, when glaciers cover much of Earth, are called. 2. Warm periods that occur during ice ages are. 3. Earth has experienced many major atmospheric and changes, such as ice ages and interglacials, throughout its history. 4. The shape of Earth s varies over the course of about 100,000 years and causes climate changes. 5. The tilt of Earth s changes in cycles of approximately 41,000 years and influences climate. 6. The combined ocean and atmospheric cycle that results in weakened trade winds across the Pacific Ocean is called. 7. The tilt of Earth s axis as it revolves around the Sun causes. 8. A(n) is a wind circulation pattern that changes direction with the seasons. 9. El Niño/Southern Oscillation and monsoons are two climate patterns that result from interaction between the and the atmosphere. 10. A(n) is a period that has below-average precipitation. 11. A period of unusually high temperatures is called a(n). 32 Climate
Key Concept Builder LESSON 2 Key Concept How has climate varied over time? Directions: Put a check mark on the line before each item that provides information about climate changes long ago. 1. ice cores drilled from ice layers in glaciers and ice sheets 2. growth rings of trees 3. records of prevailing winds 4. ocean depths 5. fossilized pollen 6. ocean currents Directions: Answer each question on the lines provided. 7. What are ice ages and interglacials? 8. When did the most recent ice age begin? 9. Which type of period is Earth experiencing now? 10. How have temperatures varied during the Holocene, the current period? Climate 35
Key Concept Builder LESSON 2 Key Concept What causes seasons? A. B. Axis Axis Sun Equator Sun Equator Directions: Use the diagrams to answer each question or respond to each statement on the lines provided. 1. In which diagram does the northern hemisphere have summer? How do you know? 2. Which season does the southern hemisphere have in the same diagram? How do you know? 3. What short-term natural weather cycles occur as the season changes to summer? 4. What are solstices and equinoxes the beginning of? Climate 37
Key Concept Builder LESSON 2 Key Concept How does the ocean affect climate? Directions: Complete the paragraph by choosing word bank terms and writing them in the correct spaces. cold dry El Niño pressure warm weaken wet During El Niño, trade winds (1.) and (2.) water moves toward South America. This prevents (3.) water from upwelling and increasing the air pressure above it. As a result, the normal pattern of high and low (4.) across the Pacific is reversed. During El Niño, the climate of the western coast of South America is (5.) and warm instead of (6.) and cool. Directions: Answer each question or respond to each statement on the lines provided. 7. Define El Niño/Southern Oscillation (ENSO). 8. What is a monsoon, and what causes it? 9. What are a drought, a heat wave, and a cold wave? 38 Climate