1. Insolation
Insolation = Incoming Solar Radiation Energy in = Energy out or, Insolation In = Heat Out (Earth only emits heat)

2. Factors Angle of insolation - direct or indirect
Length of Day - how much sunshine is available.
Type of Surface:
-- light or dark
-- rough or smooth

4. Angle of Insolation

5. Angle of Insolation

6. Axis Tilted Earth’s axis tilts 23.50
Always tilts the same way = parallelism
Seasons result.

7. Parallelism

9. Seasons

10. Equinox Equinox = when the sun is directly over the equator.
Day and night are equal = 12 hours long
Sun rises due East, sets due West
Vernal (spring) Equinox = March 20
Autumnal (fall) Equinox = Sept. 22

11. Solstice Solstice = sun stop
Summer Solstice ( 6/21) = Sun is directly over N (Tropic of Cancer) = most daylight
Winter Solstice (12/21) = Sun is directly over S (Tropic of Capricorn) = least daylight

13. Rotation
Daily Motion = stars and planets rise in the East and set in the West. Why?
Earth rotates counterclockwise at 15o / hr.
Evidence:
- Foucault’s Pendulum
- Coriolis Effect – all winds move rightward in the northern hemisphere

15. Length of Day How long is a day? Is it 24 hours or 23 hrs. 56 minutes?
Sidereal Day = actual time it takes to rotate 3600 (23h 56m).
But, earth revolves around sun 10 in a day. So, it takes an additional 4 minutes to complete turn.
Solar Day = Noon to Noon = Time it takes to rotate 3610 (24h).

17. Revolution Earth revolves around Sun 1o / day. Also counterclockwise.
Evidence:
Seasons.
Constellations change during year.