Relative
Humidity is a percentage based on how much moisture is in the air
versus how much moisture the air can hold. The dewpoint is the
temperature that the atmosphere must reach for a parcel of air to become
fully saturated. That being said, if the temperature outside is 30
degrees (F or C doesn't matter), and the dewpoint goes from 10 to 20,
then the relative humidity has increased, meaning there is more moisture
present in the atmosphere.
The easiest way to look at pressure is by looking at the number of air
molecules that are in a closed container. Gas molecules expand as they
warm, so warming up a container of air means that these molecule will
attempt to expand, thus increasing the pressure. Take for instance a
soda bottle filled with air, if you heat a soda bottle, then the gases
inside will attempt to expand (raising the pressure) and eventually the
bottle will explode, but if you stick the same soda bottle in dry ice,
the soda bottle will contract, due to decreased pressure.
Source(s):
Military Meteorologist
Bachelors in Natural Science
