I was reading up on color temperature of lightbulbs, learned about blue light, as well as white light, and think it can explain the blue and white vapor we experience. It goes like this when you see blue light, or in our case blue vapor, more gas(smaller particles) are diffusing the light. When you see white light(in our case white vapor) its because more larger particles are diffusing the light. In our world this means when we see a blue vapor, we are getting a clean, pure herbal extraction of the substances we want. When we see a white cloud, we are getting more water, and dust, mixed in with the vapor. This is just a theory but, I think this is whats going on.
So, it would seem to me that a slow inhale, and a clean, dust free, room, along with very little moisture in the bud will give a a clean, blue vapor. Even if your herb has moisture in it, you can vape at low temperatures of around 230f, and this will allow the higher temp vapor to stay small which will allow better lung absorption. I'm thinking that having some type of water filter would give an even cleaner extraction because the water will clean out whatever plant fibers, or dust, that get mixed into the vapor. This is if a slow inhale is done. Also, going up in temperature with 10 degree increments will help keep the substances released from the clumping together, and becoming larger. This will waste some of the vapor because the larger the particle size, the higher the chance it will stick to the walls of the bong or whip, as well as the respiratory walls. If you read the link I gave, you will notice it states that gas molecules that are 1nm help this blue light to become more visible. Well, smoke particles are around 0.3-0.5 microns which equals to 300nm-500nm. That explains why smoke is a thick white. If we get a thin blue vapor, we know we are getting pure active ingredients from the herb, and not other unwanted things. We also know we are getting proper absorption into the alveoli, and not condensation onto the walls of the respiratory system.
I wonder if this reason is also why a strong inhale gives white thick clouds? Maybe the strong suction forces more plant fibers to mix in with the vapor, and giving the illusion that a lot is being extracted when in reality its just more dirty, and harder to absorb. If this is true it would mean we can tell how clean our extraction is just by exhaling vapor next to a daylight bulb with a color temperature of 5,000k(if you can get a higher one that is even better). I know cree, and G.E. sell daylight bulbs with this color temperature. Gotta get me some new bulbs.
Here's more on the colors, and particle effecting them:
http://www.webexhibits.org/causesofcolor/14D.html
"The variations of blue across the sky cannot be explained using the framework of the Rayleigh theory, which describes scattering by particles much smaller than the wavelength of the incident light. The Rayleigh theory holds for the scattering of visible light (with wavelengths ranging from roughly 400 to 750 nm) by atmospheric gas molecules with dimensions in the order of 1 nm (1 nanometer equals one billionth of a meter), which are considerably smaller than visible light wavelengths. Blue wavelengths are scattered downwards and the sky appears blue.
However, the molecules of gases are not the only particles contained in the atmosphere. Aerosols, such as particles of dust, smoke, droplets of liquids, minuscule crystals, bacteria, and pollens float in the lower atmosphere. The typical dimensions of such particles can lie anywhere between several hundred and more than ten thousand nanometers. When these aerosols are comparable to, or even larger than, the wavelength of the incident light, a different scattering model applies.
German physicist Gustaf Adolf Mie (1868-1957) investigated this kind of scattering, and established that the intensity of light scattered by bigger particles is practically independent of its wavelength. In Mie scattering, white light remains white after having been scattered by particles such as aerosols. The concentration of the aerosols is highest close to the ground, and so the blue color of the sky is lightest close to the horizon where large aerosols scatter white light. The aerosols are washed out by rain, causing a deepening of the blue color of the sky following rainfall. The blue of the sky appears deeper in the mountains because lower percentages of large aerosols are found at higher altitudes. White light is scattered by large particles, as occurs in fog and clouds."
Definitely very interesting IMO.. I have wondered what made vapor more or less smooth for a little bit now.. I never considered the link between blue vs white vapor though.. I suspect that a increasingly decreasing temp throughout the duration of the draw makes for more harsh vapor, possibly from more vapor condensation 
, but an increasing or stable temp throughout the duration of the draw makes for smoother vapor 
