Connecting the Weather Air Masses Fronts Jet Stream Quiz Midweek Seminars Meteorology Jet Streams Fronts and Air Masses Air Masses A mass of air takes on Temperature and Moisture from where the ID: 617372
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Meteorology – Jet Streams Fronts and Air Masses
Connecting the Weather
Air Masses
FrontsJet StreamQuiz
Midweek SeminarsSlide2
Meteorology – Jet Streams Fronts and Air Masses
Air Masses
A mass
of air takes on Temperature and Moisture from where the source of air originates.Source Region - Land or SeaAmount of Time over the Source regionModification as the Air Mass moves away from the source.
Midweek SeminarsSlide3
Meteorology – Jet Streams Fronts and Air Masses
Air Mass Classification and humidity
Artic – Polar Ice Cap in Winter
Polar – Forms 40’ to 60’, Summer up to 80’Tropical – Forms from high pressure cells, Summer over large continentsEquatorial – Region between Sub tropical HighsHumidity depends on sourceMaritime – Forms over
Water – more humid
Continental – Originates over
Land – less humid
Midweek SeminarsSlide4
Meteorology – Jet Streams Fronts and Air Masses
Midweek Seminars
Air masses affecting the UK a
re either Polar or
Tropical with Artic
air mass in winterSlide5
Meteorology – Jet Streams Fronts and Air Masses
What happens as an Air Mass moves from
Cold to Warm?
Air becomes heated in the Lower LevelsTo pilot this gives you..Unstable AirWarmer AirLow HumidityMidweek Seminars
What happens as an Air Mass moves from
Warm
to
Cold?
To
pilot this gives you..
More stable air
Colder in lower levels
Increased
HumiditySlide6
Meteorology – Jet Streams Fronts and Air Masses
Air Masses
Polar Maritime
Source – Greenland & IcelandConditions at SourceColdStable
High Humidity
As Air Mass moves South East becomes
Unstable resulting in
Cu and
Cb
over Land
Heavy Showers, Rain, Hail
Moderate to severe Icing
Good
Visibility
Midweek SeminarsSlide7
Meteorology – Jet Streams Fronts and Air Masses
Air Masses
Tropical Maritime
Source – AzoresConditions at SourceWarmSlight Instability
Moderate Humidity
As Air Mass moves North East Air cools from
below
Advection Fog
St &
Sc
by day
St at night
Poor
Visibility
Midweek SeminarsSlide8
Meteorology – Jet Streams Fronts and Air Masses
Air Masses – Tropical continental
Source – North Africa
Conditions at SourceWarmStableLow Humidity
As Air Mass moves North it cools from below becomes more stable, Humidity stays low
.
Hot & Dry weather
Poor Visibility due to
Haze
Midweek SeminarsSlide9
Meteorology – Jet Streams Fronts and Air Masses
Air masses, Arctic Maritime,
W
inter only Source – Artic CircleConditions at SourceCold
Stable
Low Humidity
As Air Mass moves South it is heated from below becomes VERY unstable,
Cold
Moist - Precipitation
Heavy Snow
Cu &
Cb
Clouds
Unstable
Possible Thunderstorms
Midweek SeminarsSlide10
Meteorology – Jet Streams Fronts and Air Masses
Air Masses, Polar continental, Winter only
Source – Siberia & North Europe
Conditions at SourceColdStableLow Humidity
As Air Mass moves over cold land of Europe it stays cold and
stable
Cold
Very Dry
No Precipitation
Possible Thunderstorms along east coast if Air Mass has moved over North
Sea
Midweek SeminarsSlide11
Meteorology – Jet Streams Fronts and Air Masses
Midweek SeminarsSlide12
Meteorology – Jet Streams Fronts and Air Masses
Midweek Seminars
Coffee!!!!!Slide13
Meteorology – Jet Streams Fronts and Air Masses
When Air Masses meet we call them… Fronts
A front is a zone of transition between two contrasting air masses
The three types of front areColdWarmOccluded
The interaction of two air masses at the frontal surface frequently gives rise to a great deal of frontal cloud and weather
.
Midweek SeminarsSlide14
Meteorology – Jet Streams Fronts and Air Masses
Fronts
Typical cross section through a frontal system
Midweek SeminarsSlide15
Meteorology – Jet Streams Fronts and Air Masses
Warm front
Midweek SeminarsSlide16
Meteorology – Jet Streams Fronts and Air Masses
Warm Front Weather
Midweek Seminars
Wind veers & increases slightly
Temperature /
Dewpoint
rise.
Pressure steadies
Precipitation changes from RA to DZ or DZRA.
Cloud changes from NS to ST or SC
.Slide17
Meteorology – Jet Streams Fronts and Air Masses
Cold Front
Midweek SeminarsSlide18
Meteorology – Jet Streams Fronts and Air Masses
Cold Front Weather
Midweek Seminars
Pressure rises rapidly
Wind veers and decreases slightly
Temp / Dew point fall.
Visibility improves
Intermittent Rain Heavy Showers begin from NS /
Embd
CbSlide19
Meteorology – Jet Streams Fronts and Air Masses
Midweek SeminarsSlide20
Meteorology – Jet Streams Fronts and Air Masses
Warm Occlusion
Air Masses
FrontsJet StreamQuiz
Midweek Seminars
Less cold air
over-rides
colder air ahead.Slide21
Meteorology – Jet Streams Fronts and Air Masses
Cold Occlusion
Midweek Seminars
Colder air
under-cuts
less cold air aheadSlide22
Meteorology – Jet Streams Fronts and Air Masses
Midweek SeminarsSlide23
Meteorology – Jet Streams Fronts and Air Masses
Jet Streams
Midweek Seminars
A jet stream is an river of high velocity air with velocities of 60 – 250kt, on rare occasions 300kt flowing generally west to east
It is a wind belt in created by thermal wind in a boundary zone between warm and cooler air
i.e.
a frontal zone. It usually separates the colder and warmer air.Slide24
Meteorology – Jet Streams Fronts and Air Masses
Jet Streams
Max wind speed in a Jet Stream is found on the warm side of the frontal zone at an altitude just above than of the cold
tropopause and below that of the warm tropopause and the direction usually agrees with that of the front.Midweek SeminarsSlide25
Meteorology – Jet Streams Fronts and Air Masses
Connecting the Weather
Interpretation of
Wx infoTips for en route Wx interpretation and cross referencing Met chartsExample: F215 shows vis 999 ocnl SHRA 4km vbis cloud 2500 ocnl 1500METAR 9999 BKN 2500 SHRA ; TAF 9999 BKN 2500 PROB30 TEMPO 5000 +SHRAAIRMET Says cold front with gusting winds passing early in day, isolated heavy showers laterConclusion, flight can go ahead, choose alternate carefully and proceed with caution.
Midweek SeminarsSlide26
Meteorology – Jet Streams Fronts and Air Masses
Quiz
Define CAVOK
More than 10k vis, no cloud below 5000ft or MSA, no CuNim in vicinitySHSNRA VV003Heavy showers of snow or rain, vertical visibility 300ftAn airmet says Cold Sector. Conditions?Colder dryer air, good vis, scattered cumulusMETAR : EGLF 031450Z 02012KT 6000 BKN017 04/00 Q1034. Flyable?
Yes
METAR
: EGLF 031450Z 02012KT 9000 OVC005 04/04 Q1004. Flyable?
No
TAF says PROB30 TSRA BKN 020 flyable?
Yes with caution
PROB50 Exists?
No, any more than PROB40 is BCMG or TEMPO
Midweek Seminars
Met Office website
Form 214-215
TAFs, METARs, AIRMET
Other sites, XCweather.co.uk, avbrief.co.uk, sky demonSlide27
Meteorology – Why it’s a bad idea to bypass proper Met planning
Midweek Seminars