Mnemonics and Main Memory Items | MET | Air masses and Fronts Flashcards
Wind characteristics with fronts NH:
- Ahead of the warm front -
- At the warm front -
- Warm sector(between the cold and warm front) -
- At the cold front -
- Behind the cold front -
- Steady increasing, slightly backing, usually southerly.
- Sharp veer
- Steady, usually from SW
- Sharp veer, gusts and squalls likely due to CB
- Steady or slight veer
Behind the cold front NH:
Surface W/V - Temperature - Dew Point - Pressure - Cloud - Precipitation - Visibility
Surface W/V - Steady or slight veer to NW.
Temperature - Steady low.
Dew Point - Steady low.
Pressure - Rises slowly.
Cloud - 6/8, base lifting, Cu, Cb.
Precipitation - Showers, heavy at times, hail and TS possible.
Visibility - Very good, except in showers.
At the cold front NH:
NH
Surface W/V - Temperature - Dew Point - Pressure - Cloud - Precipitation - Visibility -
Surface W/V - Sharp veer, gusts and squalls likely.
Temperature - Sudden fall.
Dew Point - Sudden fall.
Pressure - Starts to rise.
Cloud - 6/8 to 8/8, base low but rising, Cu, CB, sometimes Ns.
Precipitation - Heavy rain or snow showers, thunder and hail possible.
Visibility - Good, except in precipitation.
Warm sector NH:
Surface W/V - Temperature - Dew Point - Pressure - Cloud - Precipitation - Visibility -
Surface W/V - Steady, usually from the SW.
Temperature - Steady.
Dew Point - Steady.
Pressure - Slight fall.
Cloud - 6/8 to 8/8, some large breaks may occur, base low, St, Sc.
Precipitation - Light rain, drizzle
Visibility - Poor, possibly advection fog in winter.
At the warm front NH:
Surface W/V - Temperature - Dew Point - Pressure - Cloud - Precipitation - Visibility -
Surface W/V - Sharp veer. Temperature - Sudden rise. Dew Point - Sudden rise. Pressure - Stops falling. Cloud - 8/8, base very low, Ns, St. Precipitation - Moderate or heavy continuous. Visibility - Very poor, fog can occur
Ahead of a warm front NH:
Surface W/V - Temperature - Dew Point - Pressure - Cloud - Precipitation - Visibility -
Surface W/V - Speed increasing, slight backing, usually southerly.
Temperature - Steady low.
Dew Point - Steady low.
Pressure - Steady fall.
Cloud - Increasing to 8/8, base lowering, Ci, Cs, As, Ns.
Precipitation - Light continuous from As becoming moderate to heavy continuous from Ns.
Visibility - Reducing to poor.
The area lying between the two fronts is known as -
The type of weather -
The warm sector
Stratus and stratocumulus
Clouds associated with a warm front -
CI, CS, AS, NS and SC.
Clouds associated with a cold front -
CU, CB and AC
The passage of a warm front can be associated with areas of fog. The types of fog just in advance and just after the passage are respectively
frontal fog and advection fog
What will be the effect on the reading of an altimeter of an aircraft parked on the ground as an active cold front is passing?
It will first increase then decrease
A decrease in pressure will cause the altimeter to increase, and vice-versa
Pressure characteristics of a cold front:
Approaching cold front -
At the cold front -
behind the cod front -
steady decreasing
steady Increasing
slowly rising
In which approximate direction does the centre of a frontal depression move?
In the direction of the warm sector isobars
The depression tends to move in a direction parallel to the first two isobars in the warm sector.
An occlusion has the characteristics of a warm front when
the cold air behind is warmer than the cold air ahead
In a warm front occlusion:
the warm air is lifted
How to tell whether it is a cold occlusion or warm occlusion on a chart?
The occlusion will follow the line of the air mass it is associated with. I.E
Warm front occlusion will follow the warm front line
Cold front occlusion will follow the cold front line
Which occlusion:
X occurs when a fast moving cold front is colder than the air ahead of the slow moving warm front. When this occurs, the cold air replaces the cool air and forces the warm front aloft into the atmosphere. Typically, the cold front occlusion creates a mixture of weather found in both warm and cold fronts, providing the air is relatively stable.
A cold front occlusion
Which occlusion:
X occurs when the air ahead of the warm front is colder than the air of the cold front. When this is the case, the cold front rides up and over the warm front. If the air forced aloft by the warm front occlusion is unstable, the weather is more severe than the weather found in a cold front occlusion. Embedded thunderstorms, rain, and fog are likely to occur.
A warm front occlusion
Between a warm front occlusion and a cold front occlusion, which will provide the worst weather?
Warm front occlusion
Mnemonic to remember occlusions:
Which ever pushes the other up, is the dominant front type.
If the cold air is pushed up, it is a warm front occlusion.
If the warm air is pushed up, it is a cold front occlusion.
If shown a chart of the front cross section, and two lines that intersect is shown -
It’s an occlusion
Which is true of a secondary depression in the northern hemisphere?
It tends to move round the primary in a cyclonic sense
What is encountered during the summer, over land, in the centre of a cold air pool?
Showers and thunderstorms
How do you recognize a cold air pool?
As a low pressure area aloft (e.g. On the 500 hPa chart)
The region of the globe where the greatest number of tropical revolving storms occur is:
the north west Pacific, affecting Japan, Taiwan, Korea and the Chinese Coastline
Thunderstorms in exceptional circumstances can occur in a warm front if:
the warm air is convectively unstable
The boundary between polar and tropical air is known as:
Polar front
The arctic front is the boundary between:
polar air and arctic air
When do cold occlusions occur more frequently in Europe?
Summer
The passage of a warm front can be associated with areas of fog. The types of fog just in advance and just after the passage are respectively
frontal fog and advection fog
