ENEC 202 Lab- Milankovitch cycles

Aphelion

the point at which the Earth is furthest from the sun

Angle of incidence

the angle between the sun’s rays and the surface of the Earth

measured as deviation from the perpendicular

varies diurnally (daily)

Eccentricity

The shape of Earth’s orbit

The cycle of change is 100000 years

Irradiance

the density of insolation at a perpendicular plane to the sun’s rays

A function of the temperature of the sun and the distance between the sun and Earth (inverse square law)

as distance increases, density of insolation decreases

Insolation

incoming solar radiation

Intensity

density of insolation

varies with the angle of incidence

Obliquity

Earth’s tilt

Cycle of change is 82000 years

Perihelion

the point at which Earth is closest to the sun

Positive feedback

When a perturbation on a system initiates a feedback loop that drives the system in the same direction as the perturbation

Precession

The orientation of Earth’s poles relative to the plane of Earth’s orbit

cycle is 26000 years

What are we doing in this lab

Calculating insolation and how that changes at different points in the Earth’s orbit

Milankovitch’s theory

Earth’s ice ages were initiated when high latitudes in the Northern Hemisphere receive minimal summertime insolation- ice never melts, extent of ice increases at winter time and this increases albedo which means a decrease in insolation absorbed by Earth, positive feedback loop

Seasons

Caused by the irradiance (power of EM radiation per unit area) received from the sun at a given point on Earth- this chnges as the Earth orbits the sun

Summer is not when closest to sun, but when that pole is tilted towards the sun