050 06 00 00 AIR MASSES AND FRONTS

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050 06 00 00 AIR MASSES AND FRONTS

 

050 06 01 00 Air masses
050 06 01 01 Description, classification and source regions of air masses

(01) Define the term ‘air mass’.
A large area with broadly the same, characteristics.

 

(02) Describe the properties of the source regions.

From the equator, warm, dry over land, moist over water.

From the poles, cold, dry over land, moist over water.

 

(03) Summarise the classification of air masses by source regions.

Tropical maritime (mT) Warm and moist.

Tropical continental (cT) Warm low humidity.

Polar maritime (mP) – Starts cold and dry the picks up moisture as it travels over the warmer Atlantic.

Arctic maritime (mA) – Winter – Cold and saturated.

Returning polar maritime (rmP) – Extended route over the Atlantic. Unstable over the sea then becomes stable in the lower layers as it swings round to the north.

Polar continental – (cP) – Summer. Warm and dry.

 

 

(04) State the classifications of air masses by temperature and humidity at source.
Above

 

(05) State the characteristic weather in each of the air masses.

Tropical maritime (mT) Begins warm and moist – Moves north east becomes more stable as it’s cooled from below. High humidity means condensation. Fog, low cloud, drizzle and poor visibility in winter. Cloud dispersed if it moves over land in summer.

Tropical continental (cT) Moving into higher latitudes, it gets cooled from below, more stable, not very much cloud. High temperatures and poor vis with no cloud.

Polar maritime (mP) – Starts cold and dry then picks up moisture as it travels over the warmer Atlantic. Cumulus or CB, showery, good visibility. Most of Europe’s unstable weather comes from here.

Arctic maritime (mA) – Unstable and showers, that rarely reach England.

Returning polar maritime (rmP) – Becomes stable returning to the north but may be unstable in its higher layers.

Polar continental – (cP) – Summer – hazy, dry conditions.

 

(06) Name the three main air masses that affect Europe.

Tropical maritime and polar maritime and I suppose tropical continental.

 

(07) Classify air masses on a surface weather chart.

— first letter: humidity
• continental (c)
• maritime (m)
— second letter: type of air mass
• arctic (A)
• polar (P)
• tropical (T)
• equatorial (E)
— third letter: temperature
• cold (c)
• warm (w)

050 06 01 02 Modifications of air masses

(01) List the environmental factors that affect the final properties of an air mass.

The properties of the area it moves to: Temperature, pressure, terrain and if it moves across water or land.

 

(02) Explain how maritime and continental tracks modify air masses.

Increases or decreases the relative humidity.

 

(03) Explain the effect of passage over cold or warm surfaces.

Warm from below increasing the ELR reducing stability. Cool from below reducing the ELR and increasing stability.

 

(04) Explain how air-mass weather is affected by the season, the air-mass track and by orographic and thermal effects over land.

Seasonal temperature variation, so the same track can produce different weather depending on the season.

 

(05) Assess the tendencies of the stability of an air mass and describe the typical resulting air-mass weather including the hazards for aviation.

Assessing what air mass you are dealing with as discussed earlier.

 

 

050 06 02 00 Fronts
050 06 02 01 General aspects

(01) Describe the boundaries between air masses (fronts).
Because of the different densities, different air masses tend to not mix.

 

(02) Define ‘front’ and ‘frontal zone’.
The front is where the two air masses meet and the frontal zone is the entire ground area that the meeting takes place.

 

(03) Name the global frontal systems (polar front, arctic front).
Yep, named…

 

(04) State the approximate seasonal latitudes and geographic positions of the polar front and the arctic front.

About 50° latitude, the northern one moves about a bit 35°N down to 65°N, but the southern one stays white still.

 

 

050 06 02 02 Warm front, associated clouds and weather

(01) Define a ‘warm front’.
Where a warmer air mass is forced towards the colder air, being less dense it rides above and cloud can form.

 

(02) Describe the cloud, weather, ground visibility and aviation hazards at a warm front depending on the stability of the warm air.

High cirrus, cloud base lowers into altostratus, then nimbostratus. Can be very think. Can be from the ground to the tropopause. Freezing rain and/or drizzle can take a day to pass when over cold land in winder or prolonged rain in summer.

 

(03) Explain the seasonal differences in the weather at warm fronts.
Just did…

 

(04) Describe the structure, slope and dimensions of a warm front.
1:150 ish, all the weather is in front of the ground position up to 600-700 nm ahead.

 

(05) Sketch a cross section of a warm front showing weather, cloud and aviation hazards.
Do it yourself.

 

 

050 06 02 03 Cold front, associated clouds and weather

(01) Define a ‘cold front’.
When cold air is forced into cold. The slope is not as shallow as a warm front and a little nose type think forms.

 

(02) Describe the cloud, weather, ground visibility and aviation hazards at a cold front depending on the stability of the warm air.
Similar cloud to a warm front, cirrus at the top the Cirostraus the altostratus. The nose thing traps some of the warm sector underneath creating large instability and dramatically increasing the ELR, this result in CU, CBs and nasty showers

 

(03) Explain the seasonal differences in the weather at cold fronts.

Winter and summer we get TSU

 

(04) Describe the structure, slope and dimensions of a cold front.

1:50-1:75 30-50 nm wide.

 

(05) Sketch a cross section of a cold front showing weather, cloud and aviation hazards.
No

 

 

050 06 02 04 Warm sector, associated clouds and weather

(01) Describe fronts and air masses associated with the warm sector.

Tropical maritime. The pressure drops a bit until the cold catches up with a westerly wind

 

(02) Describe the cloud, weather, ground visibility and aviation hazards in a warm sector.

Winter over the Atlantic and NW Europe, Typically tropical maritime. Widespread low stratus, clear skies if humidity is low. Summer, fair weather cumulus over land. If the air is tropical continental, clear skies. Dry air may inhibit clouds.

 

(03) Explain the seasonal differences in the weather in the warm sector.
Above

 

(04) Sketch a cross section of a warm sector showing weather, cloud and aviation hazards.
No…

 

 

050 06 02 05 Weather behind the cold front

(01) Describe the cloud, weather, ground visibility and aviation hazards behind the cold front.

CBs and stratiform cloud sloping up as in a warm front. Unstable air as it is cold air traveling generally south and getting warmed. Improved visibly because of this instability. Gust fronts and squalls reduce and so does the wind after the front passes.

 

(02) Explain the seasonal differences in the weather behind the cold front.
In winter the CU can bring snow.

 

 

050 06 02 06 Occlusions, associated clouds and weather

(01) X Define the term ‘occlusion’ and ‘occluded front’.
Cold travels faster than warm until the meet.

 

(02) Describe the cloud, weather, ground visibility and aviation hazards in a cold occlusion.
The weather of both types of front. Clouds ahead similar to a warm front.

 

(03) Describe the cloud, weather, ground visibility and aviation hazards in a warm occlusion.
Usually in winter. In winter there is rain, sleet, snow. In summer heavy period of rain.

 

(04) Explain the seasonal differences in the weather at occlusions.
Above.

 

(05) Sketch a cross section of occlusions showing weather, cloud and aviation hazards.
No

 

(06) On a sketch illustrate the development of an occlusion and the movement of the occlusion point.
No

 

 

050 06 02 07 Stationary front, associated clouds and weather

(01) Define a ‘stationary front’.
<5 kts Isobars parallel. Weather depends on stability. Weather can be persistent for days..

 

 

 

 

050 06 02 08 Movement of fronts and pressure systems, life cycle

(01) Describe the movements of fronts and pressure systems and the life cycle of a mid-latitude depression.
Movement influenced by the jet streams. The front is formed between the hot and cold air masses, this develops into a wave, the cyclonic circulation is established. Then the occlusion begins to form at the centre of the low. This cold front starts chasing the warm across the Atlantic until the occlusion is fully developed. The it dissipates.

 

(02) State the rules for predicting the direction and the speed of movement of fronts.
Moves perpendicular to the front inline with the isobars behind. Speed is the geostrophic interval at the front concerned.

 

(03) State the difference in the speed of movement between cold and warm fronts.
Cold is faster hence the occlusion. Cold = geostrophic, warm 70% of…

 

(04) State the rules for predicting the direction and the speed of movement of frontal depressions.
Moves parallel to the isobars in the warm sector and the speed depends on the geostrophic interval along the warm sector.

 

(05) Describe, with a sketch if required, the genesis, development and life cycle of a frontal depression with associated cloud and rain belts.
Can be bothered.

 

 

050 06 02 09 Changes of meteorological elements at a frontal wave

 

(01) Sketch a plan and a cross section of a frontal wave (warm front, warm sector, and cold front) and illustrate the changes of pressure, temperature, surface wind and wind in the vertical axis.
Look at some pictures…