1. WOTD:Solstice: when the tilt of the Earth's axis is pointing toward or away from the Sun Equinox: When the earth is not tilted toward or away from the sun, and the hours of daylight and night are equal… L.T: I can explain why we have seasons DO NOW: ON WORKSHEET! HW: Seasons Worksheet Ms. Ware ~ Earth Science ~ 11/16/09

2. Seasons What causes the seasons? http://nix.ksc.nasa.gov/info

3. True color images June December March September http://www.nasa.gov/vision/earth/features/blue_marble.html

4. What Causes Earth’s Seasons? Earth’s axis is tilted 23.5 degrees – it always points in the same direction (Polaris, the North Star) as we orbit our Sun once a year This tilt causes the seasons! http://www.lpi.usra.edu/education/skytellers/seasons/about.shtml

6. Insolation: INcoming SOLar raDIATION More daylight hours, more direct sunlight Northern Hemisphere Summer http://www.lpi.usra.edu/education/skytellers/seasons/about.shtml

7. Animation http://esminfo.prenhall.com/science/geoanim ations/animations/01_EarthSun_E2.html http://esminfo.prenhall.com/science/geoanim ations/animations/01_EarthSun_E2.html

8. Earth’s orbit is almost a perfect circle Perihelion: When Earth is CLOSEST to our Sun (91 million miles) in winter—January 3 Aphelion: When Earth is farthest from on our Sun (94 million miles) in summer –July 4

9. Figure 6h-6: During the equinoxes, the axis of the Earth is not tilted toward or away from the Sun and the circle of illumination cuts through the poles. This situation does not suggest that the 23.5 degree tilt of the Earth no longer exists. The vantage point of this graphic shows that the Earth's axis is inclined 23.5 degrees toward the viewer for both dates (see Figures 6h-3 and 6h-4). The red circles shown in the graphic are the Arctic Circle.

10. Height of Sun for USA Winter: The Sun rises in the southeast, stays low in the sky, and sets in the southwest. Spring: The Sun rises due east, moves higher in the sky than in winter, and sets due west. Summer: The Sun rises in the northeast, travels high (near zenith), and sets in the northwest. Fall: The Sun rises due east, travels to a medium- height in the sky, and sets due west.

11. Daylight Hours Across the Globe Time is indicated as number of hours (h) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 10.5 h 11 h 12 h 12.5 h 13 h 14 h 14.5 h 14 h 12.5 h 12.5 h 11 h 11.5 h 14.5 h 13.5 h 13.5 h 12.5 h 11 h 11 h 11 h 11.5 h 11.5 h 12.5 h 14 h 14.5 h 12 h 12 h 12 h 12 h 12 h 12 h 17.5 h 15.5 h 13.5 h 11.5 h 10 h 8.5 h 8.5 h 9.5 h 11.5 h 13 h 15 h 16.5 h 5 h 7 h 10 h 13.5 h 17.5 h 21.5 h 22 h 18 h 15.5 h 11.5 h 8.5 h 5.5 h 12 h 12 h 12 h 12 h 13 h 13 h 12 h 12 h 12 h 12 h 12 h 12 h 15 h 14 h 13.5 h 12.5 h 11.5 h 10 h 10.5 h 11 h 11.5 h 12.5 h 14 h 14 h 9 h 10 h 11 h 13.5 h 15 h 17 h 16.5 h 15.5 h 13.5 h 11.5 h 10.5 h 9.5 h 24 h 24 h 19 h 14.5 h 0 h 0 h 0 h 0 h 7 h 15 h 24 h 24 h Miami Brisbane Nairobi Punta Arenas Nome Singapore Cape Town Seattle Vostok http://www.lpi.usra.edu/education/skytellers/seasons/activities/light.shtml

12. Seasons on Other Planets In some cases, the changing distances from the Sun will affect the seasons. In others, the axial tilt will make a huge difference!

13. Seasons on Planets Planet Axial Tilt Eccent. OrbitPerihelion Aphelion Mercury 0° 0.21 88 days 28 mill. Miles 43 mill. miles Venus 177° 0.01 224 days Earth23° 0.02 365 days 91 mill. miles 94 mill. miles Mars 25° 0.09 686 days 129 mill. miles 155 mill. miles Jupiter 3° 0.05 12 years Saturn 27° 0.06 30 years Uranus 98° 0.05 84 years Neptune 30° 0.01 165 years

14. Mars’ Orbit and Seasons At summer solstice, Mars is 153 million miles from the Sun At autumnal equinox, Mars is 134 million miles from the Sun At winter solstice, Mars is 128 million miles from the Sun At vernal equinox, Mars is 145 million miles from the Sun Original images from http://photojournal.jpl.nasa.gov/index.html

15. C. The four seasons do not occur in the tropics. These areas receive nearly direct sunlight year-round, so temperatures are high and consistent throughout the year.

16. DRAWING TIME!!! 15 mins In groups color and label your seasons diagram….then answer the questions below: 1.)Draw the Equator (red crayon) 2.) Draw tropic of cancer (23.5 N) and tropic of capricorn (23.5 S) 2.) Label the summer and winter solstice 3.) Label the vernal (spring) and fall (autumnal) equinox 4.) Draw light from the sun (yellow) ~Hint the light should only be able to hit ½ of the earth at once Answer these questions: 1.) What causes the seasons? 2.)Why is it hotter in the Northern Hemisphere at position A on your worksheet? 3.) At the equator, there are no summers or winters, only wet and dry seasons. Why is this so? 4.)If the earth were not tilted in its orbit, how would the climate and seasons be affected?

17. Final Summary: Answer these questions in your notebook What causes the seasons? Why is it hotter in the Northern Hemisphere at position A on your worksheet? At the equator, there are no summers or winters, only wet and dry seasons. Why is this so? If the earth were not tilted in its orbit, how would the climate and seasons be affected?

18. How is it that Alaska is dark from… November 18 th - January 23 rd NEW PROBLEM!!!! AHHHH!!!