Earth's revolution around the sun.If you live in the Northern Hemisphere, you probably know that autumn began on September 22. The leaves are falling, and nights are getting cooler. But in the Southern Hemisphere, spring his just begun. Why is there such a difference? The illustration above shows why. Because the Earth is tilted as it revolves around the sun, the sun's direct rays strike different parts of the planet at different times of the year. This causes the change in seasons. Four Special Days On September 22, 2004, the direct rays of the sun were at the equator, which is at 0 degrees latitude. This marked the beginning of autumn in the Northern Hemisphere. On December 21, 2004, the sun's rays will directly strike the Tropic of Capricorn Tropic of Capricorn, parallel of latitude at 23°30' south of the equator; it is the southern boundary of the tropics. This parallel marks the farthest point south at which the sun can be seen directly overhead at noon; south of the parallel the sun appears less , an imaginary line In general, an imaginary line is any sort of line that has only an abstract definition, and does not exist in fact. As a geographical concept, an imaginary line may serve as an arbitrary division (such as a border). at 23[degrees] 27'S (23 degrees, 27 minutes south latitude). That will mark the beginning of summer in the Southern Hemisphere, when the sun's rays strike south of the Antarctic Circle Antarctic Circle, imaginary circle on the surface of the earth at 66 1-2°S lat., i.e., 23 1-2° north of the South Pole. It marks the southernmost point at which the sun can be seen at the winter solstice (about June 22) and the northernmost point of the all day long. On March 20, 2005, the sun's rays will again shine directly on the equator. But this time, spring will begin in the Northern Hemisphere. And on June 21,2005, the sun's rays will directly shine on the Tropic of Cancer Tropic of Cancer, parallel of latitude at 23°30' north of the equator; it is the northern boundary of the tropics. This parallel marks the farthest point north at which the sun can be seen directly overhead at noon; north of the parallel the sun appears less than , which is 23[degrees] 27'N. The sun's rays will strike north of the Arctic Circle Arctic Circle, imaginary circle on the surface of the earth at 66 1-2°N latitude, i.e., 23 1-2° south of the North Pole. It marks the northernmost point at which the sun can be seen at the winter solstice (about Dec. all day long. Study the diagram, then answer the questions. QUESTIONS 1. Which day in 2004 marked the beginning of autumn in the Northern Hemisphere?-- 2. The sun's rays directly hit which latitude that day?.-- 3. On December 21, 2004, the sun's rays will directly strike which named line of latitude Noun 1. line of latitude - an imaginary line around the Earth parallel to the equator parallel of latitude, parallel, latitude polar circle - a line of latitude at the north or south poles ?-- 4. That day will mark the beginning of which season in the Southern Hemisphere?-- 5. Which season in the Northern Hemisphere?-- 6. The sun's direct rays will strike which line of latitude on March 20, 2005?-- 7. That day will mark the beginning of which season in the Northern Hemisphere?-- 8. On June 21, 2005, the sun's rays will be seen for 24 hours Adv. 1. for 24 hours - without stopping; "she worked around the clock" around the clock, round the clock a day north of which line of latitude?-- 9. Nearly all places on Earth receive an equal amount of daylight and darkness on which two days?-- 10. Does Earth rotate in a clockwise or counterclockwise direction? (See white arrows at the North Pole North Pole, northern end of the earth's axis, lat. 90°N. It is distinguished from the north magnetic pole. U.S. explorer Robert E. Peary is traditionally credited as being the first to reach (1909) the North Pole. In 1926, Richard E. .)-- ANSWERS 1. September 22. 2004 2. The equator (0[degrees] latitude) 3. Tropic of Capricorn 4. Summer 5. Winter 6. Equator (0[degrees] latitude) 7. Spring 8. Arctic Circle 9. September 22, 2004 and March 20. 20.05 10. Counterclockwise |
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