Amount of moisture present in the air.
Weight of water present in the air.
Amount of moisture present in the air compared to the amount the air could hold at that temperature and pressure.
Temperature to which the air must be lowered to bring about saturation.
Is cooled by the cold air underneath.
Is cooled by the surrounding cold air aloft.
Becomes unstable as a result of cooling from below.
Cools as a result of expansion as it rises.
Moist air moves from a warm surface to a colder surface.
The cold ground cools the air in contact with it at night
Moist air is influenced by orographic effect.
Moist cool air moves from a cold surface to a warm surface.
Clockwise around high and low pressure areas.
Counter-clockwise around high and low pressure areas.
Clockwise around a high pressure area and counter-clockwise around a low pressure area.
Counter-clockwise around a high pressure area and clockwise around a low pressure area.
Veers and increases.
Backs and increases.
Backs and decreases.
Veers and decreases.
Veer and increase in speed.
Veer and decrease in speed.
Back and increase in speed.
Back and decrease in speed.
Moist air, high temperature, and an inversion.
Stratus cloud, high humidity and a lifting force.
Unstable air, high humidity and a lifting force.
A mixing of two different air masses.
A low pressure area.
A reverse temperature condition.
An inverse convection condition.
Strong winds, cumulus cloud, good visibility.
Uniform temperature, good visibility.
Continuous rain, freezing temperature.
Fog, poor visibility and layer cloud.
Narrow zone of fog between a cyclone and an anticyclone.
Line of thunderstorms.
Narrow transition zone between two air masses.
Mass of layer cloud which is very thick and which covers a wide area.
Warm air is compressed as cold air rides over it.
Temperature rises owing to increased pressure.
Fog will always form from the interaction of warm and cold air.
Warm air is lifted as colder air pushes under it.
The passage of a cold front.
The passage of a warm front.
Clearing skies and a decrease in temperature.
The pressure altitude.
The true altitude.
Expected at a station at a given time.
Expected at a station over a 12 hour period.
Observed at a station at the time of the report.
Observed at a station during the previous day.
300 degrees at 8 kts.
070 degrees at 70 kts.
180 degrees at 5 kts.
050 degrees at 6 kts.
3/8 to 5/8 of the sky covered in clouds height of the layer 13'.
5/8 to less than 8/8 of the sky covered in cloud, height of the layer is 13,000'
Trace to 2/8 of the sky covered in cloud, height of the layer 1,300'