EAE3132 Theme 2 The Physical Science Basis

Radiation

Transfer of energy by rapid oscillations of electromagnetic fields

Wavelength

Crest to Crest distance

Amplitude

Peak to trough distance

Emissivity

Effectiveness in emitting thermal radiation

Higher the temperature of an emitting object

Shorter the wavelength of radiation, greater the amount of radiation

Planks Law

Allows us to show the complete wavelength distribution of radiant energy from black bodies at different temperatures 

Stephan Boltzmann’s Law

The total thermal energy radiated per unit surface area of a black body per unit time is directly proportional to the fourth power of its absolute temperature

Wien’s Displacement Law

States that a rise in temperature increases the proportion of shorter wavelengths in a radiation

Short wave radiation

Radiation emitted from the sun

Long wave radiation

Terrestrial radiation

Absorption

Produces a change in the internal energy status of the absorber, followed by emissions related to an increase in temperature

Scattering and reflection

Produces no change in the energy status of the object

Stratosphere

Ozone abundance is greatest

Radiant energy

Associated with electromagnetic waves propagating through space

Thermal energy

Energy associated with the ability of one body or substance to raise the temperature of a cooler one

Potential energy

Energy due to position

Kinetic energy

Energy due to motion

Conduction

Transfer of energy in a substance by means of molecular excitation without any net external motion

Convection

Transfer of energy by mass motions within a fluid or gas, resulting in actual transport of energy

Milankovitch Cycles

Long-term, periodic changes in Earth's orbit and rotation that control how much sunlight reaches our planet and drives ice age cycles

Eccentricity

Shape of the Earth’s orbit around the sun shifts from circular to elliptical over a period of 100,000-400,000 years

Obliquity

The tilt angle of Earth’s rotational axis varies between 22.1º and 24.5º over a cycle of about 41,000 years

Precession

Slow wobble of Earth’s rotational axis produces a circle every 26,000 years