Milankovitch Cycle

Dr. ELCHS APES

Milutin Milankovitch

•Serbian astrophysicist is best known for developing one of the most significant theories relating Earth motions and long-term climate change

http://tpema.free.fr/Images%20TPE/milankovitch_portrait.jpg

Eccentricity

•The shape of the Earth's orbit around the Sun

•Constantly fluctuating, orbital shape

•More and less elliptical (0 to 5% ellipticity)

•Cycle of about 100,000 years. http://www.homepage.montana.edu/~geol445/hyperglac/time1/milankov.htm

http://www.homepage.montana.edu/~geol445/hyperglac/time1/milankov.htm

Axial Tilt

•Oscillations in Earth's axial tilt

•Periodicity of 41,000 years

•21.5 to 24.5 degrees

•Today - tilt is about 23.5 degrees

•Periodic variations of this angle vary the severity of the Earth's seasons changeshttp://www.homepage.montana.edu/~geol445/hyperglac/time1/milankov.htm

http://www.homepage.montana.edu/~geol445/hyperglac/time1/milankov.htm

Procession

•Earth's slow wobble as it spins on axis

•Wobbles from pointing at Polaris (North Star) to pointing at the star Vega

•Periodicity of 23,000 years

•Changes the timing of the seasons

http://www.homepage.montana.edu/~geol445/hyperglac/time1/milankov.htm

Anim

atio

n

Wave Addition

or Fourier Analysis

http://www.tonmeister.ca/main/textbook/node188.html

Constructive

http://www.tonmeister.ca/main/textbook/node188.html

Constructive

http://www.tonmeister.ca/main/textbook/node188.html

Destructive

http://www.tonmeister.ca/main/textbook/node188.html

Destructive