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Pressure systems

Depressions or Lows

Anticyclones or Highs

Cols

Troughs

Ridges

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CAE NLS sect6 TB 2

Frontal depressions

Non-frontal depressions:

Thermal low Orographic low

Polar Low

Cold pool, low aloft

Tropical Cyclones/storms

Tornadoes, dust whirls, dust devils

depressions

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CAE NLS sect6 TB 3

NH

N

Z

Wave development

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CAE NLS sect6 TB 4

EEN DEPRESSIE-FAMILIE

Kleindochter

Dochter

MoederBlz 6.3 2de alinea

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ISOBARENPATRONEN

Ridge

Ridge

trough

H

Temporary

cold high=

Trek-

hoog

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CAE NLS sect6 TB 8

In frontal depressions , this one is first!!!

Next slide, Jet stream!

When DIV > CONV:

Surface Low willdeepen!

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CAE NLS sect6 TB 9

EEN DEPRESSIE-FAMILIE

Kleindochter

Dochter

MoederJet stream*

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Frontal depressions

If there is an area of divergence in the upper air above the polarfront lowpressure development will occur at the surface

frontal wave

active weather (stratiform clouds/rain)

Cold low = frontal low

= dynamic lowLet op de

drukvlak-

ken!!!

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CAE NLS sect6 TB 11

Non-frontal depressions:

thermal depression (sim Sea Breeze)

thermal depression = warm low

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CAE NLS sect6 TB 12

Orographic lowstuwrug

lijvore

L

wind

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CAE NLS sect6 TB 13

stuwrug

berg

wind

opstapelen

druktoename

te kort

drukafname

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Lee trough after Rocky Mountains

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Polar Low

Small depression in lower level (< 15.000 ft) in winter time

formed in arctic or polair air over warmer water.

ELR becomes unstable when low is moving south over

warm water.

Cb, mainly snowshowers. CBs are the mainsource of energy, similar to Tropical Cyclones

500 hPa

1000 hPa

sfc

L

http://upload.wikimedia.org/wikipedia/commons/1/1e/Polar_low.jpg

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CAE NLS sect6 TB 16

Cu streets over

warm water

Greenland

Little showers

Big(ger)

showers

http://upload.wikimedia.org/wikipedia/commons/1/1e/Polar_low.jpghttp://upload.wikimedia.org/wikipedia/commons/1/1e/Polar_low.jpg

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Cold pool (Koude Put)

cold air in upper level

increasing unstability

summer thundershowers

winter snowshowers/snow

500 hPa

1000 hPa

sfc

L

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CAE NLS sect6 TB 18

Tropical cyclone (page 8.20 ev)

Clusters or walls of big showers organizing

around center of low

warm low because of release energy from

condensation in showers

Most intense weather system on

earth!!!

Showers up to 16 km!

Cyclostrophic winds (Gradient wind

balances centrifugal force, Coriolis is nil)

sfc

1000 hPa

500 hPa

300 hPa

L

H

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CAE NLS sect6 TB 19

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CAE NLS sect6 TB 20

BOVENAANZICHT VAN EEN VOLWASSEN TROPISCHE CYCLOON MET

EEN OOG IN HET CENTRUM

AB

100 NM

200 NM

300 NM

400 NM

Deze afmeting kan

maximaal bereikt

worden, meestal zijn

ze veel kleiner, straal

zon 200 nm.

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CAE NLS sect6 TB 21

WINDVERDELING IN EEN ROND EEN VOLWASSEN TROPISCHE

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CAE NLS sect6 TB 22

WINDVERDELING IN EEN ROND EEN VOLWASSEN TROPISCHE

CYCLOON

Isotachen*

TEMPERATUURVERDELING IN EN ROND EEN VOLWASSEN TROPISCHE

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CAE NLS sect6 TB 23

TEMPERATUURVERDELING IN EN ROND EEN VOLWASSEN TROPISCHE

CYCLOON

T 16 gradenwarmer than

average.!!!

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Hurricane Elena aug/sept 1985

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Rain an track

15.67 inch =

39,8 cm =

398 mm !!!*

http://www.australiasevereweather.com/forum/index.php?action=dlattach;topic=3289.0;attach=7030;image

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Tracks of Tropical ]cyclones

Tropical Cyclones strange movements!

Average tracks page 8.23/24

http://www.australiasevereweather.com/forum/index.php?action=dlattach;topic=3289.0;attach=7030;imagehttp://www.australiasevereweather.com/forum/index.php?action=dlattach;topic=3289.0;attach=7030;image

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CAE NLS sect6 TB 28

Names of Tropical Cyclones in the World: (page 8.23)

Hurricane (Atl Ocean / Caribean)

Typhoon (Asia, North and South Pacific)

Cyclones (Tropical Cyclones) (Indian Ocean, Australia)

(Baguio or bagyo - Old name near Philipines)

Willy Willy is a dust devil* !!!)

http://upload.wikimedia.org/wikipedia/commons/2/23/Global_tropical_cyclone_tracks-edit2.jpg

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CAE NLS sect6 TB 29

Map of the cumulative tracks of all tropical cyclones during the 1985

2005 time period. The Pacific Ocean west of the International Date Line

sees more tropical cyclones than any other basin, while there is almost no

activity in the Atlantic Ocean south of the Equator.

http://en.wikipedia.org/wiki/Pacific_Oceanhttp://en.wikipedia.org/wiki/International_Date_Linehttp://en.wikipedia.org/wiki/Atlantic_Oceanhttp://en.wikipedia.org/wiki/Equatorhttp://en.wikipedia.org/wiki/Equatorhttp://en.wikipedia.org/wiki/Atlantic_Oceanhttp://en.wikipedia.org/wiki/International_Date_Linehttp://en.wikipedia.org/wiki/Pacific_Oceanhttp://upload.wikimedia.org/wikipedia/commons/2/23/Global_tropical_cyclone_tracks-edit2.jpg

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anticyclones

warm high

cold high

subtropical high

blocking high

migration high

Subsidence

Convergence > Divergence

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CAE NLS sect6 TB 31

Warm high In the center the air is warmer than around

Warm high = dynamic high => subtropical high (Azores)

Mind the

pressure

surfaces!!

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Blz 8.2

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Cold High

Cold high = thermal high*

The air is cold, so much

denser.

Often big winter highs over a

continent (!) are Cold Highs

Siberia, Antartica

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CAE NLS sect6 TB 34

Foto: T.A. de Boer

Blocking highs Always Warm Highs: to have a barrier in the

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Blocking highs Always Warm Highs: to have a barrier in the

upper air to prevent a normal westerly flow.

They last for more than one week, sometimes month!

Long period of calm weather when you are in the

high.but bad in the lows besides*

1st Omega blocking:

jet

jet

Blocking highs Always Warm Highs: to have a barrier in the

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CAE NLS sect6 TB 36

Blocking highs Always Warm Highs: to have a barrier in the

upper air to prevent a normal westerly flow.

They last for more than one week, sometimes month!

Long period of calm weather when you are in the

high.but bad in the lows besides*

1st Omega blocking:

jet

jet

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Blocking highs

2nd: Diffluent blocking:

Jet stream*

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Migratory high* (Cold high!)

High/ridge moving between two frontal lowpressure systems

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Cols (ZADELGEBIEDEN)

Anticyclonic col curveture of high isobars is most

Cyclonic col curveture of low isobars is most

Symmetric col curveture of isobars is similar

In cols

low variable winds

often foggy (winter)

Last < week

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CAE NLS sect6 TB 40

Cols

Symmetric col

Cyclonic col

Anticyclonic col

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Herhaling Druksystemen

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CAE NLS sect6 TB 42

Frontal depressions

Non-frontal depressions:

Thermal low

Orographic low

Polar Low

Cold pool, low aloft

Tropical Cyclones/storms

Tornadoes, dust whirls, dust devils

depressions

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CAE NLS sect6 TB 43

Frontal depressions

Always Cold Lows!

Axis is tilted upwards

Upper air is behind

compared to direction of

motion!

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Non-f rontal depressions:

Thermal low

Orographic low

Polar Low

Cold pool, low aloft

Tropical Cyclones/storms

Tornadoes, dust whirls, dust

devils

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CAE NLS sect6 TB 45

anticyclones

warm high

cold high

subtropical high

blocking high

migration high

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Cold and warm, Lows and Highs

surface

Cold Low Warm Low

Warm High Cold High

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Cold and warm, Lows and Highs

surface

Cold Low Warm Low

1) Frontal low

2) Cold pool

3) Orografic low

1) Thermal Low

2) Tropical Cyclone

3) Polar Low !!!

4) Tornado

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CAE NLS sect6 TB 48

Cold and warm, Lows and Highs

Warm High Cold High

1) Subtropical Highs

2) Blocking Highs

1) Winter Highs over

continents

2) Migration Highs

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G l Ci l ti L

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H

L

General Ciculation Low

Sturend Laag/

Algemene Circulatie

Laag

N

Z

L

L

Almost stationary

Almost stationary

Subtropical High

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