1. Reasons for the Seasons
Page 69

2. Why do we have seasons on Earth?
The most common answer-and its wrong!- is that the earth is getting closer and farther from the sun.
THIS IS WRONG!!

4. It’s all about the angle of the light!

5. Which sunlight will be hotter?
Direct Light
Indirect Light

6. What is Direct Light? Light coming in straight at an object.
Concentrated in one area = HOT
When the sun is directly overhead, we get Direct Light.

7. What is Indirect Light?
Light coming in at an angle. (Sometimes called “Angled Light”)
Spread out over an area = COOL
When the sun is NOT directly overhead, we get Indirect Light.

8. What shape is the Earth?
Will sunlight hit the earth at the same angle for the entire surface of the earth?

9. some parts of the earth’s surface receive direct light, others areas get indirect light.
The Earth is a sphere…

10. therefore- some areas will get HOT, direct light, others will get cooler indirect light.
The Earth is a sphere…

11. What else can we say about the Earth?
The earth is TILTED on its AXIS.

12. What is the Earth’s AXIS?
An imaginary line that runs through the middle of the Earth
The line which the Earth rotates/ spins around.
Tilted 23.5◦

13. A tilted axis means…
The part of the earth that is receiving direct light changes throughout the year as the earth orbits the sun!

14. When do we have summer?
When our half of the Earth (Northern Hemisphere) is pointed towards the Sun

15. When our half (hemisphere) is pointed away from the sun
When do we have winter?
When our half (hemisphere) is pointed away from the sun

16. When is it the hottest?
When the sun is directly over us.

17. South of the equator the seasons are opposite of ours in the North

19. What is a SUMMER SOLSTICE?
The sun is directly over the Tropic of Cancer (23.5 N)
Longest day of the year
June 21st
First day of summer

20. What is a WINTER SOLSTICE?
The sun is directly over the Tropic of Capricorn (23.5 S)
Shortest day of the year
Dec. 21st
First day of winter

21. What is an EQUINOX?
The sun is directly above the EQUATOR
EQUAL day/night (12 hrs)
Fall Equinox Sept 21, Spring Equinox March 21