Course Glossary Flashcards
absorption
Where the energy of a photon is taken up by matter, typically the electrons of an atom (e.g. gases, aerosols absorb EM radiation).
Material can also absorb atoms or molecules (e.g. water into a sponge).
aerosol
Very fine particles suspended in the atmosphere (e.g. dust, organic carbon, sea salt). They may absorb or reflect solar radiation.
albedo
A percentage measure of reflectivity, generally refers to how much solar radiation is reflected by surface, e.g. ice has a higher albedo than the ocean.
conduction
The transfer of heat or electricity (energy) directly through the material of a substance where there is a difference of temperature (or of electrical potential- voltage) between connected regions, without actual motion of the material.
convection
The movement of matter in a fluid due to the tendency of hotter, less dense material to rise and colder, denser material to sink under the influence of gravity. This is another method of heat transfer.
eccentricity
The amount by which an object’s orbit around a body (sun) deviates from a perfect circle. Perihelion- closest point in orbit to sun, aphelion- furthest point in orbit to sun.
Energy
A property of matter that can’t be created or destroyed, but is exchanged between objects. Measured in Joules (J).
EM (electromagnetic) Radiation
Energy transmitted in the form of waves. Generated by a varying electromagnetic field. Light from the sun is a mixture of wavelengths, ranging from infrared (IR- longer wavelength) to ultraviolet (UV- shorter wavelength) waves.
(see notes for diagrams)
Frequency (f)
The number of crests (or cycles) of a wave that move past a given point over a given period of time. Usually measured in Hertz (Hz) - 1 Hz = 1 crest per second.
Infrared (IR) radiation
A type of EM radiation of longer wavelength and lower frequency than visible light. IR radiation transfers heat from one place to another- everything that gives off heat also gives off IR radiation.
Intensity
Power transferred per unit area (an imagined surface at 90° to the propagation of waves). Measured in W/m2. A measure of solar radiation.
power
Energy per unit time. Measured in Watts (W). 1 W = 1 J/s.
radiation
Energy travelling through space. Travels as both a wave and a photon. Measured in power per unit area (W/m2 or Wm-2 = 1 J s-1 m-2)
radiation spectrum
The range of wavelengths (and by consequence frequencies) emitted by radiation sources.
reflection
The change in direction of a wave at an interface (junction) between two mediums which causes the wave to return to travelling through the medium it originally came from (e.g. EM radiation can be reflected from clouds and Earth’s surface).
