'in the beggining'

which way does the earth rotate on its axis?

from east to west

what is the earths obliquity?

the angle of its rotational axis relative to the plane of its orbit

how much is the earth roughly inclined by?

23.43 degrees

how does obiliquity cause seasons from December to February?

the NH is pointed away from the sun and the SH point towards the sun therefore causing winter in the northern hemisphere and summer in the southern hemisphere

how does the angle of tilt affect seasons?

the greater the angle of tilt the more extreme the seasons

why does greater obliquity cause more extreme seasons?

1. solar radiation angle, summer sun is directly overhead at higher and higher latitudes

2. day lengths (summer days lengthen and winter days shortern)

3. expanded polar circles (24HR polar daylight at lower and lower latitudes)

is axial tilt static?

no, varies on a geological time scale ranges from 22.1 to 24 degrees

what are the tropical zones?

mark the limit of the zone where the sun is directly overhead at least once per year

what are the polar circles?

the limit of the zone where at least one 24HR period of full daylight/night

how does obliquity affect life?

stable obliquity leads to a more stable climate therefore can better support life on earth

how does the moon affect earths obliquity?

moon is large with strong gravitational stabilising influence on earths tilt which helps the earths obliquity remain stable, in comparison to mars which only has two smaller moons so is less stable

why is the earths orbit of the sun described as eccentric?

the Earths orbit around the sun is elliptical so the distance to the sun varies (deviates from a normal circle)

what does earths eccentricity cause?

causes a 6.4% annual variation in solar radiation, this varies of 100,000 to 400,000 year cycles

what is periphelion?

when earth is closest to the sun in its orbit

what is aphelion?

when earth is furthest from the sun in orbit

what is axial precession?

the movement and wobble of the earth similar to a spinning top around its axis

how does axial precession affect the pole star?

the pole star varies so isn’t always polaris

how does axial precession affect climate?

makes seasonal contrast more extreme in one hemisphere and less in the other, currently the northern hemisphere sees more extreme seasonal variation and the SH hotter and less variation

how does earths eccentricity, obliquity and precession influence the earths climate?

control the distribution of insolation received by earth from the sun

what is insolation?

the amount of solar radiation energy that reaches a specific area of the earths surface over any given time

how long is the precession cycle?

26,000 years

which orbital configuration favours ice growth?

1. low obliquity (low seasonal contrast)

2. NH summers during aphelion (cold summers in the north)

3. high eccentricity

which orbital configuration favours ice melt?

those that promote warm summers:

1. high obliquity (high seasonal contrast)

2. NH summers during perihelion (hot summers in the north)

3. high eccentricity