I've found this to be the case, too. Generally, my shop lights will flicker when turning on, especially when it is colder outside .
There are two basic phases to this kind of light bulb: a start-up phase, and an operating phase. The start-up requires more voltage, because you are initiating the plasma stream between the terminals of the bulb.
So, these bulbs are filled with gas, generally mercury vapor. When you turn it on, you're really creating an electrical arc at the end of the bulb. This arc ionizes the gas, and that is the flickering you see. Eventually, the entire length of the bulb can arc, and a plasma stream is created (plasma is just a gas of free-moving ions and electrons).
When it is cold, or if the starter arcs are wearing out (and can't produce sufficient voltage), then the flickering lasts longer. By touching the bulb, you actually provide a shorter path for the plasma stream! In effect, you get two short plasma streams, each terminating at your touch point. Then, once the plasma streams interact, and since the voltage required to maintain the stream is less than the voltage needed to establish it, the streams merge into one and the lamp will light.
This is similar to some "glowing orbs" you see in gift shops or museums... a glowing plasma (looks like lightning inside a clear spherical shell) will arc and bend toward your touch, since you are providing your own set of electric and magnetic fields.
Light travels at 300,000,000 meters per second. There is a very small period of time after switching it off where there still are photons from the bulb in the room. But these get absorbed/scattered by the wall and thus you don't see them. This what happens to all of the light that came out of the bulb significantly before you turned it off as well -- the photons (or EM radiation, take your pick) are no longer present in the room in their initial form. When the light hits the wall, some of it is absorbed, which heats up the wall ever so slightly (just how sunlight can heat things. For that matter, you can warm your hand even with a flashlight if you hold it in place fo a couple of minutes. You can do the same by placing your hand near a lightbulb). This heat dissipates through the wall. Also, some of it is scattered back with a shift in wavelength -- the electromagnetic radiation is still present in the room, but it is no longer visible. It could be radio waves/infrared waves or even ultraviolet waves. It's harmless, though. Eventually, it all leaves the room in the form of heat.
Remember, a light bulb doesn't "contain" light. It contains a filament, which glows when you pass electricity through it. This exactly what happens when you heat a metal -- the electrons get excited and start emitting visible light. Here, you are supplying energy to the bulb (in the form of electricity), and it gets heated, giving off light. For CFL bulbs the system is more complicated, but it still involves the excitation of electrons.
Best Answer
The light from a fluorescent lamp is produced by an electric current discharging through a gas, typically mercury vapour, which releases photons in the UV-range. These are then absorbed by a thin phosphor coating on the inside of the glass tube, which re-emit a photon in the visible spectrum.
In order to generate the required voltage and maintain an arc through the gas, these lamps require a 'ballast' which, in the simplest case, consist of an inductor, or a solid-state electronic circuit, which generates a high enough voltage to ionize the gas and produce a discharge current through the tube. In some cases, a 'starter' filament is used to heat a cathode which discharges electrons into the gas. This 'starter' is disconnected once electric discharge is maintained through the tube.
When a starter is old and worn, there may be insufficient discharge current through the tube to keep the gas ionized, which can result in 'blinking' at the ends of the tube, as the starter filament is brought in and out of operation.
Depending upon the type of ballast and/or starter, you may need to replace the starter, eg: some electronic ballasts incorporate a the 'starter' function, in which case you may have to change the ballast. A worn lamp is usually indicated by dark patches at the ends of the tube.
A low voltage would typically result in repeated flickering at the ends of the tube or the lamp will not light at all, depending upon how low the voltage was. Some lamps may not
The 'dark waves' which appear through the tube at low voltage are the result of insufficient temperature within the tube to achieve full ionization of the gas, which could result from a low line voltage causing the starter to malfunction.