
Energy
The ability to do work.

3 basic ways in which energy can be transferred
 1. Conduction
 2. Convection
 3. Radiation

Conduction
Occurs when a molecule or atom transfers its kinetic energy to another by colliding with it.

Convection
Kinetic energy of atoms or molecules is transferred from one place to another by physically moving the atoms or molecules.

Electromagnetic radiation
The only form of energy transfer that can take place in the vacuum of space.

The 2 models of electromagnetic radiation

Lambda
The shorthand for wavelength.

Wavelength
The mean distance between consecutive maximums or minimums of a roughly periodic pattern; usually measured in micrometers or nanometers.

Frequency
Number of wavelengths that pass a point per unit of time.

Blackbody
A theoretical construct meaning a body that absorbs and radiates energy at the maximum possible rate per unit area at each wavelength for a given temperature.

Relationship between temperature and energy emitted
The greater an object's temperature, the more radiant energy is emitted by it.

Dominant wavelength of the Sun as it approximates a 6000 K blackbody
0.483 micrometers

Dominant wavelength of the Earth as it approximates a 300 K blackbody
9.66 micrometers

Visible light
Energy in the blue (0.40.5 micrometers), green (0.50.6 micrometers), and red (0.60.7 micrometers) bands of the electromagnetic spectrum.

How are photons emitted?
Every time an electron jumps from a higher to a lower energy level, a photon moves away at the speed of light.

What is the relationship between the frequency of radiation expressed by wave theory and the quantum?
The quantum's energy (in joules) = the Planck constant (6.626 * 10 ^{34} J s) * frequency of the radiation.

What is the photoelectric effect?
Matter is heated so much that electrons break free from atoms, which are then referred to as ions. The radiation given off is unquantized, and a continuous spectrum is produced, rather than a band or series of bands. The surface of the Sun is an example.

What is radiant energy?
The capacity of radiation within a spectral band to do work.

What is the index of refraction?
The ratio of the speed of light in a vacuum, c, to the speed of light in a substance the light enters, c_{n}.

What are the 3 types of scattering?
 1. Rayleigh
 2. Mie
 3. nonselective

What are atmospheric windows?
Portions of the spectrum that transmit radiant energy effectively.

What is radiant flux?
The time rate of flow of energy onto, off of, or through a surface; measured in watts.

What is irradiance?
The amount of radiant flux incident upon a surface per unit area of that surface; measured in Watts per meter squared.

What is exitance?
The amount of radiant flux leaving a surface per unit area of that surface; measured in Watts per meter squared.

What is radiance?
The radiant intensity per unit of projected source area in a specified direction; measured in Watts per meter squared per steradian.

