1. The Four Seasons What’s tilt got to do with it?
2. Vocabulary note how the terms compare in the opposite columns Antarctic Circle Arctic Circle Tropic of Cancer Tropic of Capricorn autumnal vernal equinox solstice revolution rotation tilt axis
3. Objective <ul><li>The student can tell which factors determine the four seasons. </li></ul>The tilt of the earth, along with its 365 ¼ -day revolution, results in our seasons.
4. Axis The earth’s axis is an imaginary line that runs through the middle of the earth from the North Pole to the South Pole. The earth rotates on its axis which is tilted about 23 ½°.
5. The earth’s tilt and its revolution causes the seasons
6. Solstice A solstice is either of the two times of the year when the sun is at its greatest distance from the equator: in technical words, when the celestial equator and ecliptic reach their largest separation.
7. Stonehenge, England 2003 Thousands gather here each year for Summer and Winter Solstice celebrations. The widespread belief is that these rocks were set in ancient times to mark those days.
8. Pontiac Solstice
10. Summer Solstice The summer solstice, approximately June 21, is the first day of summer and the longest day of the year, occurring in the Northern Hemisphere when the North Pole is leaning more directly toward the sun than it does on any other day.
11. The longest day…
12. Summer in the Northern Hemisphere In June, the Northern Hemisphere is tilted toward the sun, so the people in the Northern Hemisphere have longer and warmer days.
13. long summer days During the period marked by the summer solstice , the Northern Hemisphere is warmed by more direct sunlight and days are long and hot.
14. land of the midnight sun The Arctic region is unique because during June and July each year, the sun literally does not set. There is constant daylight for about 60 consecutive days. Similarly, in winter, the sun does not rise, and there is complete darkness for two months straight.
16. winter solstice The first day of winter and the shortest day of the year. The winter solstice in the Northern Hemisphere occurs when the North Pole is leaning away from the sun. Dowth, Ireland - It is these chamber stones, and the central one in particular, which receive the beam of sunlight during the time of Winter Solstice .
17. The longest night…
18. burning daylight Many believe that Medicine Wheel, a circular rock formation in Wyoming's Bighorn Mountains, is a solar calendar built by the Plains Indians to track the sun throughout the year. The days are longer in summer and shorter in winter the further you move from the equator. It’s generally dark on a summer night in Florida by 8:30 p.m., but in Vermont, there will still be some light at 10:00 p.m.
19. When the North Pole is pointing away from the sun, the Northern Hemisphere receives only indirect sunlight; that is why winter is so much colder than summer. colder weather
20. Equinox Equinoxes occur during transition periods when the North Pole is pointing neither directly toward nor directly away from the sun; these days are marked by equal periods of light and darkness
21. Vernal Equinox This image photographed inside Cairn T at 6:51am shows the shaped beam of equinox sunlight illuminating the back stone. Over a period of about 30 minutes the beam moves to the bottom right corner of the backstone . The first day of spring occurs when the North Pole begins to lean toward the sun again.
23. Is it true that you can stand an egg on end during the Spring Equinox? The answer is YES. However, you can stand an egg on end, with a large amount of patience, on any day of the year. This myth seems to pop up every year around the equinox, with the regularity of the grass greening up in the spring.
24. Autumnal Equinox This image shows the shaped beam of equinox sunlight illuminating the back stone. The symbol on the top left of the illuminated area clearly represents the sun and the symbols with the horizontal markings may be measuring scales. The first day of autumn occurs when the North Pole begins to lean away from the sun.
26. Equinox celebrations A thousand years ago the Maya gathered around the El Castillo pyramid at the equinox to celebrate a myth with the setting sun. This symbolic mixture of sun, shadow and stone is a representation of the arrival of the great Maya god Kukulkan to the Earth.
27. Chevrolet Equinox
28. Antarctic Circle At which date would there be no sunrise in Antarctica?