The difference between water vapor and fog?

No, fog and water vapor are NOT the same thing. Fog is a cloud at ground level, and it consists of tiny droplets of liquid water suspended in air. Water vapor is H2O in the gas phase. Water vapor cannot be seen.

When water vapor is cooled to the point where it transitions from the gas phase to the liquid phase it creates tiny droplets of water which we can call fog.

Sources??? I've taught this stuff for almost 40 years.

Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of a cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated locally (such as from a nearby body of water, like a lake or the ocean, or from nearby moist ground or marshes).

Fog forms when the difference between temperature and dew point is generally less than 2.5 °C or 4 F. Fog begins to form when water vapor condenses into tiny liquid water droplets in the air.

Water vapor is the gas phase of water.

Steam and vapor are in reality the comparable component. Technically, they don’t ought to communicate with water, yet they many times do, and for this reason, they are water in its gaseous sort. Fog and clouds are the comparable component. Fog varieties somewhat in a distinctive way from different clouds, yet the two are relatively water vapor that has cooled and condensed and formed super hundreds of water droplets so small that they glide... or fall relatively slowly, many times under a million meter according to hour.

Fog is not water vapor. Vapor is a gas, it's invisible, it's water 'dissolved' in air. Fog is LIQUID water, in little droplets. Clouds also. When you can -see- it, it's not vapor, it's not steam, it's liquid.

Air can hold a certain amount of water vapor. It loses its ability to hold water when it gets colder, or when it loses pressure (like at altitude), so these changes often make water 'precipitate' out of the air. This is one way fog forms, when moist air drifts over cold ground and the ground cools the air, it can no longer hold as much humidity so some comes out as fog.

The difference is that water vapor is clear, or "invisible". It's a gas mixed with the air. Fog is a bit different because the vapor is condensing into tiny droplets which become slightly visible. If you shine a bright light in fog when it is dark, you can see the droplets more easily.

The best I can answer this is to say that when considering differences between water vapor and fog: water vapor is JUST pure gaseous H2O, fog is what is called a colloid (or a true mixture of several gases, liquids, and solids in this case) and contains water vapor. That being said fog is the mixture of all atomspheric gases (mostly nitrogen, oxygen, and carbon dioxide), with wator in all three phases (mostly ice). So your friend is right/wrong depending on what he means... to say humid is to be warm- he is wrong, but he is no more right than you if he is considering it to be taken as moisture in the air. No doubt there is some difference in temperatures between the water vapor and air, but it has more to do with difference in atmospheric pressure due mostly to convection (i.e. wind). I hope this helps

Water vapor is evaporated water (duh)

Fog is just a cloud close to the ground. Legit.

Fog is water vapour. However, fog is defined as where visibility is reduced to less than 1km, whereas mist for example is defined for visibility not less than 1km.

its same thing, and the clouds are also water vapour