The names given to different "bands" of electromagnetic radiation are more or less arbitrary, and may vary by both name and bandwidth, depending on which user's interest is being served. For convenience I simply call it all "light" unless the discussion is centering about or specifically referring to certain regions. There aren't really different "types" of radiation in the sense that they all seem to be composed of "orthogonal (i.e. perpendicular to each other) electric and magnetic fields" which appear to propagate at the speed of light in whatever medium they find themselves in.
Your microwave oven generates "light" (which of course you cannot see) with a fairly low frequency of wave, toward the long wavelength end of the spectrum. This is similar to radar waves, which are formed in klystron tubes similar to those in microwave oven. Radio astronomers "see" across ranges of radiation at this same end of the spectrum, and they may refer to "millimeter waves".
From quantum relationships it can be shown that the greater the rate of light's vibration (its frequency) the more energy its packets of radiation carry. Visible light carries a modest amount of energy compared with ultraviolet to X-ray radiation, which is apparent from the damage that overexposure to each can cause to life forms, which mostly have developed here on Earth in an environment that is fairly well protected (by magnetosphere and atmosphere and hydrosphere) from high energy incident radiation.
In astronomy (as in other pursuits) light can be filtered by allowing a certain restricted range of bandwidths to pass through to the observer or instrument, and blocking the other, non-desired frequencies. Our atmosphere functions this way in the infrared range of the spectrum, for example, as do the large synthetic sapphire "windows" which protect infrared imaging devices on, say, aircraft. Those look "black" to our eyes, but IR passes cleanly through and an "artificial" image in light that our eyes do respond to (the visible range, sometimes called "optical") can be created, allowing us to "see" in a range of radiation which our eyes alone cannot, or to study the effects of that range and exclude unwanted light that may blur or saturate and swamp the desired range. They make "nebular filters" for telescopes which block out much ambient city light from sodium street lamps, allowing a clearer, cleaner view of faint objects such as nebulas.
Named ranges may be divided into sub-ranges, whose specific wavelengths (or frequencies, the inverse of wavelength) are usually specified by some standardization agency. Infrared is often said to be composed of "near" (nearer to the optical range), "mid" and "far" infrared. Ultraviolet (UV) has similar nomenclature.
Sometimes the term "ionizing" radiation is used, which is a gauge of its energy content, usually rated in electron-volts (eV), as to whether it can ionize this or that atom or molecule, each of which has a certain minimum energy input requirement to separate the outer or "valence" electrons from the nucleus. Generally, ionizing radiation starts in the UV band somewhere and goes up in frequency and energy per photon from there. Infrared vibrates too slowly and has too little energy to dissociate electrons from atoms so it is not ionizing radiation in most cases I can think of. Understanding this aspect of radiation is important to understanding some of the plasma physics which drives the Electric Universe. Radio waves don't ionize anything, but if they are intense enough they can sure cook you.
One simple relationship, frequency times wavelength equals the speed of light, applies at all wavelengths in any medium through which EM radiation can propagate. Light may consist of only a single frequency of vibration, as from a laser, or a tuned radio or radar transmitter. It has a single wavelength and therefore a singe frequency. Light can be very complex, such as from a star, where nearly all frequencies of light are present in varying amounts or intensities, but each "color" or wavelength has its own particular associated wavelength. The bottom line is that the shared constant is the speed of light, c, so regardless of frequency, in general all the light propagates away from the transmitter or star or source at precisely the same speed: local light speed.
For enhancing vision of very small or very distant objects, lenses are curved and have different thicknesses of glass between their outer edges so that different parts of an arriving wavefront of light from, say, IR through optical to UV) will have different lengths traveling at a slower velocity. This changes the curvature of the wavefront in order to bring it to a focus and provide a useful and faithful image, whether in a microscope or a telescope or binoculars. At much larger and smaller scales than these "mid" frequencies, other focussing techniques are required. The focusing mechanism that gathers the very short wavelength of X-ray light for the Chandra satellite telescope, among others like it, is nothing like a typical optical refracting or a reflecting telescope design. See
http://www.universe.nasa.gov/xrays/Mirr ... ptics.html and
http://en.wikipedia.org/wiki/X-ray_optics.
Don't worry if the diagrams have wavelength increasing or decreasing from left to right - that's just whatever convention the source wants to use. (The EU prefers energy (i.e. frequency) to increase from left to right on the Hertzsprung-Russel star diagram, just the opposite of the H-R diagram displayed in every standard model physics and astronomy textbook today. Remember that if the frequency is
increasing in one direction on a graph, the wavelength is decreasing, getting shorter and shorter in that direction, because their product (f x w) has to always equal a constant value, c.
To get the specific names matched to frequency bands, it's best to look up the discipline or profession you are interested in (radio astronomy, or ham radio, or radar, or X-ray, or whatever, and find what bandwidths they use and if they have names or numbers assigned to those bands of radiation. That way you know that for the ham radio enthusiast, "short-wave" radio may mean one thing, while short-wave in the Extreme Ultraviolet (EUV) might mean something more like "long-wave" to an X-ray technician who is dealing even shorter wavelengths.
Too long-winded, as usual. >sigh<
I am not sure that there are really "preferred natural units", but I'd like to see the argument. Mostly what is preferred in my world is that which relates to a life form (mine) with ten digits and a certain general length and temperature range. How and why would a base "e" logarithm ("natural log") be any more "natural" than a base 10 logarithm system, or base 2, or base pi? The definition of "natural" might be discussed first so we all understand what it is supposed to mean in this context.
Jim
