Looking at the tilt of the earth

1. The earth in motion

2. Chapter 3
 The galaxy is spinning…
 The sun is spinning….
 The earth is spinning….
 The earth is moving around the sun, while spinning on
an axis, while wobbling on that axis.
 All this motion is making me dizzy.

3. Chapter 3

4. Chapter 3
 From the previous slide it can be seen that as the earth
revolves around the sun it does not do so in a perfect
circle.
 The earths orbit is elliptical.
 The density of the earth combined with the spinning
of the earth on its axis causes it to go in this shape.
 The gravity of the sun causes the earth to try and
adjust its orbit.

5. Chapter 3
 The earth is at its greatest distance from the sun on
July 4th.
 This is the aphelion
 The earth is at its closest distance from the sun on
January 3rd.
 This is its perihelion

6. Chapter 3
 As was mentioned before, this situation changes.
 The cycle is approximately 21,000-22,000 years.
 The shift is called the precession of the equinoxes
 These variations in distance account for the differing
temperatures on the earth.
 The eccentricity of the earth is the elliptical nature of
the orbit.
 As was mentioned before, the spinning of the earth,
the differences in ass and other factors mean that the
earths orbit is not circular.

7. Chapter 3
 Since the earth is constantly trying to correct its orbit,
it goes from elliptical to near circular and then back to
elliptical.
 This is the eccentricity.
 It goes through this cycle every 100,000 years or so

8. Chapter 3
 Add on to all of this movement, the tilting of the earth
on its axis.

9. Chapter 3
 The tilt of the axis causes the seasons.
 Each of the seasons, the tilt causes one or the other
hemisphere to be more inclined towards the sun.
 This increases the amount of solar radiation that the
hemisphere receives.
 The solstice is when the sun is at its maximum
position over the tropic.
 That is the most northerly or southerly position of the
sun

10. Chapter 3
 The length of day also influence the amount of solar
radiation that a hemisphere receives.
 This also influences the temperature.
 Another factor is the amount of land mass.
 As the earth tilts, the tilt actually varies.
 The tilt varies between 21.5 degrees and 24.5 degrees
 This change occurs every 40,000 years or so and is
called the wobble

11. Chapter 3
 What is the correlation between the tilt, orbit and axis
to the earth’s ice ages?
 According to Milankovich…

12. Chapter 3—the coriolis effect
 The spinning of the earth also has an effect at the
surface level.
 If the earth were a featureless surface, the friction
caused by the surface of the earth would have minimal
influence.
 The fact that the earth has mountains, land, surging
water and other features means that the spinning of
the earth influences winds that blow across the
surface.

13. Chapter 3

14. Chapter 3
 Where do you think is the most observable place for
this phenomenon?
 Hint:

15.  The coriolis force or effect, causes the distortion of the
winds and energy as it flows towards the equator.
 What industry must take this into account?

16. Time Zones
 The final topic is the time zones that divide the earth.
 Who originated the idea of time zones?
 Hint: There is a school in Vancouver named for him.
 Hint: