Cold Front:
The leading edge of a cold air mass that is displacing the warmer air ahead of it.

Dew Point:
The temperature to which air must be cooled in order for dew (or frost, with colder temperatures) to form.

Heat Index:
The perceived temperature to the human body based on both air temperature and the amount of moisture present in the air.

High:
A region of air with higher barometric pressure and clockwise winds in the northern hemisphere; usually associated with fair weather.

Jet Stream:
Strong winds in the higher levels of the atmosphere that separate areas of different temperatures, and act as steering current for fronts.

Low:
A region of air with lower barometric pressure and counter-clockwise winds in the northern hemisphere; usually associated with stormy weather.

Relative Humidity:
The measured amount of moisture in the air relative to how much moisture could be held at a given temperature.

Stationary Front:
A boundary that separates two different air masses exhibiting little or no movement.

Warm Front:
The leading edge of a warm air mass that is displacing the colder air ahead of it.

Wind Chill:
The perceived temperature to the human body based on both air temperature and wind speed.