As long as the light source is between you and the smoke your looking at or your between the light and smoke you'll get the best light scattering to see if it's blue or more white. Otherwise you can't see a rainbow when it rains.. Like your pic with the flash on your phone etc great blue smoke. If white, then all long, med and short wave lengths can't make it through the smoke so all light is reflected back to you and see white, all the colors of the spectrum. If you see blue then all long red spectrum and med wave lengths go through TBS and only reflect the short wave length blues back to your eyes like water, glaciers and sky fine particles that reflect blue as the others go deeper. Then at dusk and dawn all wave lengths get scattered to where the longest red wave lengths can only make it to your eyes at twilight. If smoke dissipates quickly after it leaves the top vent then it's water vapor and what floats away is smoke. Shine the light at drifting smoke and it'll always be blue with an Amnps.