Warm air CAN hold more moisture than cold - reference above graph.
Relative humidity is how "full" the air is. Air, at a given temperature can hold X amount of gaseous water. %RH is % of X that is actually in the air. 40 degree C air can hold 50 grams of water per kilogram. If it is 75% relative humidity, there is actually 37.5 grams of water per kg. When relative humidity "exceeds" 100%, the excess forms clouds, rain, or snow (can't be more than 100%).
Condensate forms on your cold beer
because it is cold - nearby air gets cooled (and unfortunately warms your beer), and the relative humidity "exceeds" 100% and the water becomes liquid - surface tension puts the water on the can.
Relative humidity determines how fast water evaporates. Air is like a sponge, once it is "full" of water it won't hold anymore. A dry sponge will do a better job of mopping up spilled beer
than a wet one. You can't hang your laundry
out to dry on a 100% humid day! (Note, 100% humidity is relatively unusual, think fog
Specific humidity is the amount of moisture in the air - grams per kg in the above graph. When air goes from cold to hot, the specific humidity does not change (no water is added or removed) - but because warm air can hold more water, the relative humidity reduces. That is why warming air helps it dry things; heating
in a laundry
dryer, for example. Hot hair driers. Ovens. Etc.
The water in air is always gaseous, independent of temperature. The phase only changes from gas to liquid or solid when it condenses. If it is cold out, there may be frost on your (even colder) windshield. Ice, in turn, "evaporates" into water vapor at cold temperatures, just like water (sublimation). The rate of sublimation is a function of the relative humidity.
Don't spill your beer, drink it before it gets warm.
Wishing all smooth odor-free sailing!