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Earth-Sun Relationships and Seasons

Earth-Sun Relationships and Seasons. http://einstein.stanford.edu/highlights/sb1-112604-earth-seasons.jpg. Earth’s Motion. Tilt of Earth’s axis = 23.5 degrees. (The sun’s parallel rays are at 90 degrees in one place at one time.)

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Earth-Sun Relationships and Seasons

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  1. Earth-Sun Relationships and Seasons http://einstein.stanford.edu/highlights/sb1-112604-earth-seasons.jpg

  2. Earth’s Motion • Tilt of Earth’s axis = 23.5 degrees. (The sun’s parallel rays are at 90 degrees in one place at one time.) • Earth’s revolution around the sun = 365 days (1 year) or about 1 degree per day • Parallelism of Earth’s axis in orbit = The Earth’s axis is always pointed toward the North Star. (Parallel to itself) • Rotation on the Earth’s axis = 1 Day (24 hours)

  3. Earth’s Rotation West to East

  4. Seasons • TILT and earth’s revolution cause seasons • Most intense sunlight = summer, least intense = winter • Summer is warmer because the sunlight is more direct (intense) http://www.astronomy.org/programs/seasons/pictures/07reasons-for-seasons-flashlight.gif

  5. N What is the temperature here? (Hint: Warmer or Cooler?) What is the temperature here? Where do these guys look to see the Sun in the Sky? Direct or Indirect Ray? Direct Ray Direct or Indirect Ray? Indirect Ray Warmer Colder

  6. Indirect Ray Direct Ray Which rays from the sun are direct and which ones are indirect rays? Label them. Indirect Ray What point is receiving the most Energy? What is a direct ray? Sunlight reaches the earth at a 90 degree angle

  7. Northern Hemisphere Southern Hemisphere Which hemisphere is experiencing Winter? Which hemisphere is experiencing Summer?

  8. Summer for US is when the Northern Hemisphere is tilted toward the sun. Tilted away = WinterOpposite for the Southern Hemisphere

  9. When is it Summer? • How can you tell if it is summer or winter for us? • When the direct rays hit the northern hemisphere, then it is summer

  10. Solstice • Solstice: When the sun is at its minimum or maximum height in the sky at noon • Winter Solstice (Green Line): Lowest = Dec. 21st or 22nd –shortest day • Summer Solstice (Red Line): Highest = June 21st or 22nd;Longest day http://www.universetoday.com/wp-content/uploads/2009/03/seasons.jpg

  11. Sun’s Path – Notice Solstices Lines (Red & Green)

  12. Daylight LengthAt Winter Solstice- Dec 21 or 22 Sun is straight overhead at Tropic of Capricorn-23.5°S Every point south of Antarctic Circle experiences 24 hours of daylight. Every point north of the Arctic Circle experiences 24 hours of darkness

  13. Winter in Northern Hemisphere

  14. Daylight LengthAt Summer Solstice- June21 or 22 Sun is straight overhead at Tropic of Cancer-23.5°N Every point above 66.5°N (Artic Circle) experiences 24 hours of daylight. Every point below 66.5°S (Antarctic Circle) experiences 24 hours darkness

  15. Summer in Northern Hemisphere

  16. Summer in Northern Hemisphere

  17. Earth’s Daylight Hours at Solstices

  18. Equinox • Equinox = When the Sun’s direct rays hit the Equator. • 12 hours of daylight and darkness around the world. (Equinox = Equal daylight/Darkness) • Spring (Vernal) = March 21st -22nd • Fall (Autumnal) = September 22nd or 23rd • Neither hemisphere tilts toward the sun http://www.universetoday.com/wp-content/uploads/2009/03/seasons.jpg

  19. Notice Equinox Line (Blue)

  20. Equinox

  21. Hours of SunlightEqual at Equinox

  22. Sun’s Path • Interactive - Notice the height of the Sun during each season • Scroll down to Seasons Interactive…

  23. Earth Sun Relationships Animation from Internet Click on the Picture below http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html

  24. Earth’s Orbit Around Sun • Earth is closest to sun in WINTER- called perihelion • Cold in winter because tilted away from sun • Farthest in summer- called Aphelion • Warm in summer because tilted toward sun http://funnel.sfsu.edu/courses/gm309/labs/seasons/images/EarthsOrbitPlanView.gif

  25. Terminator Line The line that separates day from night.

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