Why are cigarette butts blue and cigarette butts white?

In fact, the color of fine particles does not depend on the color of the substance itself, but on the size of the particles. When the particle diameter is much smaller than the wavelength of light (usually about110 of the wavelength, that is, 1-300 nm), Rayleigh scattering mainly occurs, and the scattering intensity is inversely proportional to the fourth power of the wavelength of light. The shorter the wavelength, the stronger the scattering.

In the solar spectrum, the shorter wavelength is blue-violet light, so the scattering of blue-violet light is stronger. In addition, blue light has the largest energy in short wave, so it will appear blue when Rayleigh scattering occurs.

However, when the optional diameter is close to the wavelength, Michaelis scattering mainly occurs. At this time, the scattering intensity has nothing to do with the wavelength of light and the properties of photons will not change after scattering, so the light is still white after Michaelis scattering.

Particles in cigarette smoke are mainly distributed below 300 nanometers. Rayleigh scattering and Michaelis scattering work together, and the smoke is white and blue-green. Moreover, the smaller the particulate matter of cigarette smoke, the more obvious the blue color is. So the cigarette end is blue.

White smoke is spit out because the high temperature smoke takes away the moisture in the respiratory tract in the form of water vapor when inhaled; In the process of vomiting, as the temperature drops, rich smoke particles act as condensation nuclei, forming water droplets with larger diameters. At this time, Michaelis scattering is absolutely dominant, so white smoke is formed.

Whether it's blue or white, it's not good for your health.