Pre AP Geo Eccentricity Milankovitch

As the earth orbits around the sun the shape of this elliptical orbit changes over time.  The gravitation pull from Jupiter and Saturn create a number of cycles which combine more or less into a 100,000 year cycle.  When our orbit is almost circular, the eccentricity is at its minimum of 0.005 and at its maximum the value is 0.058 and currently the value is 0.017

What this means is that when our orbit is very elliptical (high eccentricity) there is a greater earth to sun difference in one year changing the solar heat input ratio.  Currently there is a 3.4% difference between the earth sun distance in aphelion to perihilion.  This earth sun difference accounts for a 6.8% variation in solar radiation.  As our orbital eccentricity increases, this variation in solar radiation also increases change the global heat balance.

Your Job is to make a Malankovitch graph which goes back 400,000 years and compare this to climate graph #3.  You will need to "follow the trend" and estimate to complete your graph.

Season durations^[5]

Year	Northern Hemisphere	Southern Hemisphere	Date: GMT	Season duration
2005	Winter solstice	Summer solstice	21 December 2005 18:35	88.99 days
2006	Spring equinox	Autumn equinox	20 March 2006 18:26	92.75 days
2006	Summer solstice	Winter solstice	21 June 2006 12:26	93.65 days
2006	Autumn equinox	Spring equinox	23 September 2006 4:03	89.85 days
2006	Winter solstice	Summer solstice	22 December 2006 0:22	88.99 days
2007	Spring equinox	Autumn equinox	21 March 2007 0:07	92.75 days
2007	Summer solstice	Winter solstice	21 June 2007 18:06	93.66 days
2007	Autumn equinox	Spring equinox	23 September 2007 9:51	89.85 days
2007	Winter solstice	Summer solstice	22 December 2007 06:08

US Naval Observatory Data

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