1. Reasons for the Seasons

2. Earth- Sun Relationships
Weather and climate almost completely driven by the sun
Energy from the sun varies with location and season
Earth is unevenly heated
This leads to weather

3. Nearly 150 million kilometers separate the sun and Earth, yet solar radiation drives Earth's weather.
At it’s Surface, the earth maintains an average temp of 59F
With a wide range of temperature readings
-121F during the Antarctica night
122F in deserts

4. Does the distance from the Sun make the Seasons?NO
The Earth is actually farther away from the Sun when we have our Summer.
July 6th
January 3rd

5. Perihelion- Earth is closer to the Sun January 3rd

6. Aphelion- Earth is farthest from the Sun July 6th

7. Solar energy creates seasons
Because the Earth is tilted, each hemisphere tilts toward the sun for half the year
Results in a change of seasons
Equatorial regions are unaffected by this tilt, so days average 12 hours throughout the year

8. What is the angle of the tilt of the axis?
Reason for the Seasons
1. The Earth’s tilt causes the seasons
It is tilted at 23.5 degrees
What is the angle of the tilt of the axis?
23.5°

9. The angle of the sun’s radiation hitting the Earth impacts the climate or temperature.

10. If the tilt were the only factor, then every location on Earth would have one season and it would never change.

11. Earth Earth rotates once per day
Rotation accompanied by revolution around the sun every days
Earth moves 113,000km/ hr around the sun

12. 2. Earth’s Revolution
Causes the Suns rays to strike at different locations as the Earth orbits the Sun.

14. When northern hemisphere is facing the sun:
•Summer Solstice June 21st or 22nd

15. SUMMER SOLSTICE Most direct rays over Northern Hemisphere
Striking at Tropic of Cancer 23.5° N
Light = 15 hours (about (NC) Dark = 9 hours

16. SUMMER SOLSTICE Most direct rays over Northern Hemisphere
•Striking at Tropic of Cancer 23.5° N.
Light = 15 hours (about (NC) Dark = 9 hours

17. Antarctica is completely dark for 24 hours and the Arctic is completely light for 24 hours!!!

18. Fall Equinox (September 22 or 23)

19. Direct rays over Equator:
EQUAL amounts of daylight and darkness everywhere.
Direct rays over Equator:
Light = 12 hours Dark = 12 hours

20. Winter Solstice - December 21-22
SHORTEST DAY !!!
Most direct rays over Southern hemisphere •Striking at Tropic of Capricorn 23.5°S
Light = 9 hours Dark = 15 hours

22. Winter Solstice - December 21-22
SHORTEST DAY !!!
Most direct rays over Southern hemisphere •Striking at Tropic of Capricorn 23.5°S
Light = 9 hours Dark = 15 hours

24. Spring Equinox (March 21 or 22)

25. Direct rays over Equator:
EQUAL amounts of daylight and darkness everywhere.
Direct rays over Equator:
Light = 12 hours Dark = 12 hours

26. The Southern Hemisphere has opposite Seasons than us . . . WHY?

28. Solstices and Equinoxes
Makes no sense without caption in book

29. Light - Year The unit used to measure stellar (star) distance.
The distance that light travels in one year.
9.5 x 1012 kilometers a year.
180,000 miles per second.