Circle of Illumination -- the imaginary line that passes divides the globe into a night-half and a day-half (sometimes called the Terminator).
Subsolar Point -- the point at which the sun's rays strike the earth directly (at a 90o angle).
Solar constant--the amount of energy that arrives from the sun at the top of the atmosphere on a plane perpendicular to the sunÕs rays. For the earth, this averages out to be around 2 cal per cm2 per min. This is often written 2 cal/cm2/min.
Emission--produced by or given off by...
Electromagnetic Radiation--the form of energy emitted by any object that has a temperature greater than 00K. (Often called radiation.). Characterized by wavelength and intensity (amount).
Insolation--the amount of radiation that after passing through the atmosphere makes it to the surface of the earth.
Laws of Radiation--physical principles that govern the amount and characteristics of the electromagnetic energy emitted by an object.
Electromagnetic Spectrum--the collection of wavelengths of radiation possible in the universe
Solar Spectrum--the collection of wavelengths of radiation emitted by the sun.
Terrestrial or EarthÕs Spectrum--the collection of wavelengths of radiation emitted by the earth.