1. Earth-Sun Relationships
The Reasons for the Seasons

2. Notebook Setup
On page 17, glue down “The Reason for the Seasons” worksheet
On page 18, glue down “Seasons Chart”

3. Warmup
What season are we in right now?
What characteristics does this season have?

4. Agenda Notebook setup Warmup Reason for the Season worksheet
Seasons Chart

5. The Four Seasons #4 #1 #3 #2

6. Please label the Tropic of Cancer (the dotted line) on globe #1

8. Why is it hot in the tropics and cold at the poles?

9. #1
The Earth is curved and tilted, which causes varying intensities of solar radiation.

10. Why is it hot in the tropics and cold at the poles?
Direct rays (most intense) are always in the tropical latitudes (23.5 º S to 23.5º N)
These are called the Tropic of Capricorn (South) and the Tropic of Cancer (North)
As a result, solar radiation is diffused in the polar regions (think about the last slide)

11. What causes the seasons?#2
What causes the seasons?
Rotation of the Earth on its axis
Revolution of the Earth around the sun

12. #2
Please label the Equator (solid line) on globe #2

13. Tilt
The Earth has a 23.5°tilt

14. Rotation of the Earth #3 Sunrise and sunset (east to west)
Rotation period is 24 hours = one day

15. Please label the Tropic of Capricorn (dotted line) on globe #3

16. Revolution of the earth#4
One revolution around the sun is 365 days
Elliptical orbit
93 million miles average distance

17. #4
Please label the Equator (solid line) on globe #4

18. Seasons Chart
Please turn to the “Seasons Chart” on page 18 of your notebook
Using your Chromebooks and a partner, please look up the seasons, the latitude of vertical sun’s rays, the relationships of day to night, and the specific name for the day
Hint: the name for the day will either be “Solstice” or “Equinox”

19. Which parts of the earth are the darkest and lightest the longest?
SOLSTICES
Summer Solstice: June 21
Direct rays are hitting the
Tropic of Cancer
This is summer for the
Northern Hemisphere, and
winter for the Southern
Hemisphere
Winter Solstice: December 21
Direct Rays are hitting the Tropic of Capricorn
This is summer for Southern Hemisphere, and winter for the Northern Hemisphere
Which parts of the earth are the darkest and lightest the longest?

20. Notice these four important parallels.
Where do they occur? Why?
When do the North and South Poles get all day sun or all day night?
Tropic of Cancer at 23.5º N
Tropic of Capricorn at 23.5º S
Arctic Circle (66.5 º N)
Antarctic Circle (66.5º S)

21. EQUINOXES
Spring, MARCH 21
Fall, SEPTEMBER 21

22. Effects of the Seasons Changes in solar intensity
Changes in solar altitude
Changes in day length
Changes in temperature
All of these changes are most extreme at high latitudes and minimized at the equator.