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What is the milankovitch cycle?
Long term variations in Earth leading to increase / decrease in how much Sun the Earth receives.
Eccentricity?
Shape of the Earth’s orbit
Normally a circular orbit becoming an elliptical orbit therefore uneven solar energy, cooler summers and a glacial period.
Over 100,000 year periods
Axial tilt?
Angle between orbital plane and rotational plane.
22.1 to 24.5 degrees where the lower the angle, the less difference between Summer + Winter temperature leading to cooler summers and a glacial period.
Over 41,000 year period
Currently at 23.4 degree
Precession?
Wobble of Earth’s axis relative to Polaris
Earth wobbles like a spinning top - changing when seasons occur within an orbit
North Hemisphere Summers occur when Earth is furthest from Sun (tilting away) leading to cooler summers and a glacial period
Every 26,000 yearw
Milankovitch cycle where all 3 align?
Every 100,000 years all 3 align to form a glacial period.
Solar variation
Radiation from the Sun varies
Low solar activity - cooler periods
High solar activity - warmer periods
Volcanism
Large-scale volcanic eruptions eject ash + dust in the atmosphere
Some eruptions produce so much that it blocks radiation from the Sun
Reduced temp
Glacial period
1816 year without summer because of Mount Tambora
Surface Impact
Large space objects impact Earth’s surface
Releasing volumes of dust to atmosphere, blocking soler radiation and causing glacial periods
Asteroid impacting climate was responsible for the dino excinction not the general impact.
3 ways for evidence of climate change?
Ice cores
Tree ring
Historical source
Albedo
Reflectiveness of a surface
High albedo - very reflective
Low albedo - absorbs energy
What albedo does ice have?
High albedo
How can ice sheets exacerbate global warming?
Ice has a high albedo therefore reflects solar radiation away. When it melts it reflects less away therefore more intense ground heating