Insolation

Insolation = Incoming Solar Radiation

Energy in = Energy out

or,

Insolation In = Heat Out (Earth only emits heat)

Factors

1. Angle of insolation - direct or indirect

2. Length of Day - how much sunshine is available.

3. Type of Surface:-- light or dark-- rough or smooth

Angle of Insolation

Angle of Insolation

Axis Tilted

Earth’s axis tilts 23.50

Always tilts the same way = parallelism

Seasons result.

Parallelism

Seasons

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 20Autumnal (fall) Equinox = Sept. 22

Solstice

Solstice = sun stop

Summer Solstice ( 6/21) = Sun is directly over 23.50 N (Tropic of Cancer) = most daylight

Winter Solstice (12/21) = Sun is directly over 23.50 S (Tropic of Capricorn) = least daylight

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

Length of DayHow 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).

Revolution

Earth revolves around Sun 1o / day.

Also counterclockwise.

Evidence:Seasons.Constellations change during year.