I remember, as a fifteen year old in summer camp, making the following observation. Normally when having a cigarette, after exhaling the smoke the smoke would disperse rather quickly. When it was rainy weather however, it seemed to me that the smoke would linger in the air a bit longer. I could give no reason for it at the time, and it was just an observation. Having just had a cigarette tonight in the rainy weather I noticed it again, now however, I think I have a hypothesis as to why this is.
When you exhale smoke, you are not just exhaling smoke. When the smoke is in your lungs, it gets attached to water molecules there. When you blow out the smoke, you are really blowing out smoke attached to water vapor. This can be noticed by the change in color in the smoke from before inhalation (when it is blueish) to after exhalation (when it is more whiteish grayish). The reason for this is the same reason why the sky is blue but the clouds are gray/white. When light hits a bunch of particles, if the particles are small enough there will be an effect called Raleigh scattering. The effect of this scattering is that the smallest wavelength of light will be scattered the most, which in most cases blue. However if the particles are bigger, all colors will scatter equally, leaving it white. The particles in smoke and in our atmosphere are small enough that the light will scatter blue, while water vapor in clouds or in our breath are too big therefore all colors are scattered equally.
When it is dry outside both the smoke and water vapor get easily dispersed in the air; however when it is rainy outside there is a lot of water in the air, and therefore the smoke mixed with water vapor takes longer to get dispersed in the air.
This is just a hypothesis, I don’t actually know if this is true. I’m pretty sure about all of it except for the fact that the water vapor in the smoke will cause the mixture of smoke and water vapor to disperse more slowly.
On a related note, don’t start smoking, it’s a bitch of a habit and I have been trying to quit for years. DON’T SMOKE.