Why does water vapor condense at the dew point?

Answer 1

At the dew point temperature, the air is so moist, it can no longer hold any more moisture. At this point, the air is cool enough for water molecules to join together around particles such as dust. The reason behind this is compacting force of cold, which is the absense of heat. When there's more heat, the water molecules move faster and avoid coming together. Basically, heat creates higher pressure, and spreads water molecules out.