1. Seasons Notes Brigitte Steinmetz John Adams Middle School

2. Disclaimer The images, maps and diagrams in this presentation were taken from the public domain on the world wide web. Permissions were granted where possible. Any privately owned images not available for this non-commercial, educational project will gladly be removed. E-mail: steinmetz@smmusd.org

3. Cause of Seasons Misconception – seasons caused by the distance b/n sun & Earth…this is FALSE! Misconception – seasons caused by the distance b/n sun & Earth…this is FALSE! Seasons are caused by the tilt of the Earth! Seasons are caused by the tilt of the Earth! http://www.weathersavvy.com /Seasons2.htmlhttp://www.weathersavvy.com /Seasons2.html - 9/22/2003

4. What if… The Earth wasn’t tilted… The Earth wasn’t tilted… –Almost every place on Earth would receive the same sunlight energy each day. How boring!

5. The power of the Sun! Drives our weather Heats the atmosphere Provides energy for plant growth – food Drives the water cycle Helps power our cars/homes – solar panels

6. Tilted Earth & the Sun Why do we (Santa Monica – Northern Hemisphere) have different amounts of sunlight during different times of the year? http://www.weathersavvy.com/Seasons2.htmlhttp://www.weathersavvy.com/Seasons2.html - 9/22/2003

7. Tilted Earth & the Sun 3 Months – N. Pole tilted toward the sun. 3 Months – N. Pole tilted toward the sun. –Summer in Northern Hemisphere –Winter in Southern Hemisphere 3 Months – N. Pole tilted away from the sun. 3 Months – N. Pole tilted away from the sun. –Winter in N. Hemisphere –Summer in S. Hemisphere 6 Months – N. Pole is neither tilted toward or away. 6 Months – N. Pole is neither tilted toward or away. –Spring or Fall

8. Why different seasons? http://www.weathersavvy.com/Seasons2.htmlhttp://www.weathersavvy.com/Seasons2.html - 9/22/2003 Figure 1 – Sunlight is concentrated. More sun energy in a smaller area. Figure 2 – Sunlight is less intense/bright. The same amount of sun energy is spread out over a bigger area. During the summer time in the N. Hemisphere (N. Pole tilted toward the sun), sunlight is more concentrated on the Northern Hemisphere (like Figure 1).

9. Why different seasons? Amount of Daylight… Amount of Daylight… –When the N. Pole is tilted toward the sun it causes the N. Hemisphere to stay in the daylight period longer. –Summertime (12-15 hours of daylight) = longer days = more time for sun to heat things up! Be careful…the concentration of the sun over an area has more of an effect…

10. Poles and Daylight 3 months out of the year the poles receive 24 hours of sunlight… 3 months out of the year the poles receive 24 hours of sunlight… –But the poles are always COLD…Why? Equator always receives 12 hours of sunlight. Equator always receives 12 hours of sunlight. –But the equator is always HOT…Why?

11. Unequal Heating Sun energy is concentrated at the equator (HOT) while energy from the sun is spread out over the polar regions (COLD)! http://www.foshay.k12.ca.us/Curriculum/Science/Public%20Science%20Day/OCE /Weather/cw.htmlhttp://www.foshay.k12.ca.us/Curriculum/Science/Public%20Science%20Day/OCE /Weather/cw.html (November 9, 2002)

12. Causes of Seasons Earth’s Tilt Earth’s Tilt http://www.weathersavvy.com/Seasons2.htmlhttp://www.weathersavvy.com/Seasons2.html - 9/22/2003 N. Pole titled toward the sun. Summer in N. Hemisphere b/c Sunlight is more concentrated & N.H. has longer days. N. Pole titled away from the sun. Winter in N. Hemisphere b/c Sunlight is less concentrated & N.H. has shorter days. What season is it in the Southern Hemisphere? Figure 1 - Winter Figure 2 - Summer

13. Climate Zones Equator N. Pole S. Pole b/n Equator & Poles Tropical Polar Temperate Polar

14. Shorter Rays = Direct Longer Rays = Spread Out Northern Hemisphere Southern Hemisphere # Rays? 7 7 3 3