1. Which city receives the most constant insolation year round?
WHY?

3. Why do THESE THREE THINGS change?
Angle of insolation determines how Earth heats.
(greater angle = greater energy)
What determines the angle of insolation?
Season, Latitude, Time of Day
Why do THESE THREE THINGS change?

4. One reason is Earth’s 23.5o tilt. The other reason is how Earth moves.
NOT LIKE THAT!

5. Earth has several motions. We will only consider two :
ROTATION- spinning on its own axis. REVOLUTION- orbiting around the sun.

6. 23h 56m 4s d

7. Rotation and revolution are independent movements that occur at the same time!

8. Rotation
Earlier
(not yet noon)
Later
(past noon)
12 Noon

9. Rotation
Not
Facing
Sun
Facing
Sun

10. Rotation
SUN
MOON

11. Rotation
15o /hr !

12. Rotation is responsible for:
Day and Night Cycle
Time zones and longitude
Celestial objects moving through sky (moon, stars, planets, etc.)
Coriolis Effect (we’ll discuss later in year)
WHICH ONE CHANGES THE ANGLE OF INSOLATION?

13. Revolution

14. Revolution

15. Revolution

16. Revolution
Sun in January photo.
Sun in July photo.

17. Revolution is responsible for
Seasons
Visibility of constellations
Apparent size of sun
WHICH ONE CHANGES THE ANGLE OF INSOLATION?

18. In New York State, summer is warmer than
winter because in summer New York has
(1) fewer hours of daylight and receives low angle
insolation
(2) fewer hours of daylight and receives high angle
(3) more hours of daylight and receives low-angle
(4) more hours of daylight and receives high angle
insolation