Air temperature, water temperature, relative humidity, wind, pressure. Explain why condensation occurs primarily when the air is cooled. Molecules are moving slower and have time to electromagnetically adjust their positioning relative to each other so as to attract to one another. When this happens water vapor is condensing into water droplets.
Absolute humidity is a mass to volume ratio and a variety of factors can influence the volume.
An example factor would be the pressure changing due to altitude. The other humidity measures do not change with altitude, pressure, or other factors. The actual vapor pressure is self-explanatory. The saturation vapor pressure is the amount of vapor pressure that the air could hold at that particular temperature. The saturation vapor pressure primarily depends on the amount of air pressure that is contributed by the water molecules striking the outer layer of a parcel of air.