Milankovitch Cycles

Milankovitch Cycles

Milankovitch Cycles▪ Eccentricity▪ Precession▪ Obliquity

Eccentricity = Orbit▪ The orbit of the Earth changes over

thousands of years.

▪ Earth's orbit ranges from an almost exact circle (eccentricity = 0.0005) to a slightly elongated shape (eccentricity = 0.0607).

▪ Currently, Earth’s orbit is an eccentricity of 0.016.

▪ Larger eccentricity means further from the sun, causing global cooling, or ice ages.

▪ Occurs in a cycle of about 100,000 years

Precession = Wobble

▪ Precession refers to the wobbling of the Earth’s axis, much like a top wobbles as it spins.

▪ Occurs in cycles of about 20,000 years.▪ We are used to the North pole pointing

toward the North star. When it wobbles, it points toward Vega.

Obliquity = Tilt

▪ Variations in obliquity involve changes in the Earth’s tilt.

▪ The Earth’s tilt ranges from 22.1o and 24.5o. ▪ A larger tilt of the Earth causes more extreme

seasons - hotter summers and colder winters.

▪ The lower the tilt is, the less intense the seasons are. This allows snow to build up, since it isn’t melted away in the summer.

▪ Occur in a cycle of about every 40,000.

Changes in Tilt

Obliquity = Tilt

▪ Eccentricity impacts overall climate the most.