Section2 TB Meteo

7/28/2019 Section2 TB Meteo

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CAE NLS-Hoofddorp 1

Section 2: Thermodynamics

water vapour

temperature

stability

Thermodynamics= change of energy(heat/warmth) in work and reverse)


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CAE NLS-Hoofddorp 2

radiosonde

temperature T TSK

humidity Td

pressure height

wind*

transmitter


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CAE NLS-Hoofddorp 3


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CAE NLS-Hoofddorp 4


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CAE NLS-Hoofddorp 5


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CAE NLS-Hoofddorp 6


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CAE NLS-Hoofddorp 7

500

600

700

800

900

1000

2 4 6 10 20 30

0 10 20 30

pressure

temperaturedry adiabatic

wet adiabatic

mixing ratio

Thermodynamical diagram (TEMP)

g/kg

C C C

pressure


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CAE NLS-Hoofddorp 8


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CAE NLS-Hoofddorp 9

solid

liquidgas

Change of state of aggregation

From higher density to lower density = Energy neaded (+)

From lower density to higher density = Energy release (-)

+ E

- E

+ E+ E

- E- E


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CAE NLS-Hoofddorp 10

solid

liquidgas

Water:

Ice

VapourWater

melt

freeze

evaporate

condens

EvaporateSublime

Deposit (in meteo*

sublimation)


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-10 0 10 20 30

30

20

10

C

hPa

T = 15 C

E = 17 hPa

e = 11 hPa

Td = 8 C17

Max. watervapour E

8 15

11

Rh = 11/17*100%

= 65 %

e

T

SATURATED

UNSATURATED


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E

hPa

E

0C

t

dam

pdruk

IJS

ONDERKOELD

WATER


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de grootte van E is afhankelijk van

DE TEMPERATUUR

DE KROMMING VAN HET WATEROPPERVLAK

DE AANWEZIGHEID VAN NIET OPGELOSTESTOFFEN


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VERLOOP VAN DE DAMPSPANNING BOVEN EEN

WATEROPPERVLAK

e

E

Water

Er is altijd een zeer dun laagje boven een wateroppervlak waar de

relatieve vochtigheid (Rh=Relative Humidity) 100% is: E

Het water wil verdampen (Saturate): De moleculen springen eruit!


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p

e

RT

p

8

31

)(.

)(

)/(

)/(

2

3

hParwatervapoueairforconstR

KetemperaturT

mNPapressurep

mkgdensity

Dry air is more heavy than moist air

e >


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Measuring watervapour in the air

psychrometer

15

T

8

Td

12

Tw

T

hPa

e

?? Dry

Bulb=

Droge

bol

T Tw(ater)

Wet

Bulb=

Natte

bol

E


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Moisture parameters

wetbulb temperature (Tw)

watervapour pressure (e)

dewpointtemperature (Td) (wordt bepaald via Tw)

mixing ratio (x) amount of watervapour in gr/kg

dry air

Relative humidity can be influenced by:

1. Rising/dropping of temperature2. More/less watervapour

3. Combination 1 & 2


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Adiabatic processes*

Process in which rising air is cooling due to the

expanding of the air, or warming due to

compressing by descending.

No heat exchange with surrounding !!


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Dry* air: ALWAYS!!

3C/1000 ft

~1 100 m

Saturated*air: VARYING !!

05000 ft: 1.8 (2)**C/1000 ft ~0,6 100 m

5000-TROP: 2-3* C/1000 ft

20

12

Dry Adiabatic Laps

Rate =

DALR

Saturated Adiabatic Laps

Rate =

SALR


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High in troposhere:

1. Low temperatures, cold

2. Cold air cant hold moist

Conclusion:

DALR reaches SALR !!!

SALR

DALR


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Dauwpuntskromme (Td) Vocht

Temperatuurkromme

= TSK (ELR)

Toestandskromme

of

Environmental

Lapse Rate ELR


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100% HUMID = CLOUDS

Tropopause


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Oefeningetje

1) T surface

2) Td surface

3) 0-degree level

(FZL*)

4) T, Td en RV op

500hPa (ca 18000

ft)

5) Height of

Tropopause (km

and ft)6) T at tropopause

T = 15Td = 11

FZL8000 ft

Ca. 2500m

T = -18

Td = -28

RV 1: 2= 50%

33000ft

10.000m T = -54


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stableunstable

indifferent

arcel of airreturns

arcel of aircontinues

stable unstable indifferent

Stability in atmosphere

or Neutral


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stableunstable

indifferent

arcel of airreturns




or Neutral


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stableunstable

indifferent

arcel of airreturns




or Neutral


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Boek: fig 2.10 LCL (Lifting Condensation Level)

Follow mixing ratio

through Td

Follow DALR through T

1. Warm air rises

2. Td decreases viamixing ratio line

3. T decreases via DALR

4. Point they meet:

Condensation=LCL
http://upload.wikimedia.org/wikipedia/commons/8/8a/LCL-NCA.pnghttp://upload.wikimedia.org/wikipedia/commons/8/8a/LCL-NCA.pnghttp://upload.wikimedia.org/wikipedia/commons/8/8a/LCL-NCA.pnghttp://upload.wikimedia.org/wikipedia/commons/8/8a/LCL-NCA.png


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DFA versie aug2004 Adiabatics and stability 17

VERTICALE EVENWICHTSTOESTANDEN ONDERZOEKEN

MET EEN THERMODYNAMISCH DIAGRAM

We maken een paar afspraken:

We stellen ons in gedachten een pakketje lucht voor, waargeen omhulling omheen zit.

We stellen ons voor dat we dit pakketje lucht omhoog en

omlaag kunnen bewegen.We kunnen het pakketje op elk willekeurig niveau aanpakken.

De processen verlopen droog- of verzadigd adiabatisch.

rogelucht is onverzadigde lucht, waar w waterdamp in

kan zitten.


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500

600

700

800

900

1000

Stable for dry adiabatic process

TSK

Take airbell on TSK

(ELR)move airbell upwards

along dryadiabatic

Airbell colder(heavier)

than TSK

airbell will return to

its starting position

air is stable


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500

600

700

800

900

1000

2 4 6 10 20 30

0 10 20 30

unstable for dry adiabatic process

take airbell on TSK

move airbell upwards

along dryadiabatic

airbell warmer(less heavy)

than TSK

airbell will move further

upwards

air is unstable


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500

600

700

800

900

1000

2 4 6 10 20 30

0 10 20 30

indifferent for dry adiabatic process

take airbell on TSK


along dry adiabatic

airbell remains at

same level

air is indifferent

(neutral) for dry air

airbells T remains the same

temperature as environment:

so same density/weight


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500

600

700

800

900

1000

2 4 6 10 20 30

0 10 20 30

stable for saturated adiabatic process

take airbell on TSK


along saturated adiabatic

airbell colder(heavier)

than TSK

airbell will return to

its starting position

air is stable forsaturated air


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500

600

700

800

900

1000

2 4 6 10 20 30

0 10 20 30

unstable for saturated adiabatic process

take airbell on TSK



airbell warmer(less heavy)

than TSK

airbell will move

further upwards

air is unstable forsaturated air


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500

600

700

800

900

1000

2 4 6 10 20 30

0 10 20 30

indifferent for saturated adiabatic process

take airbell on TSK



airbells T remains the same

temperature as environment:

so same density/weight

airbell remains at

same level

air is indifferent for

saturated air


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exercise

On the thermodynimical diagram we take several temperatures at different levels and try to conclude if the layer

between two levels is stable, unstable or indifferent for dry and for saturated air.

1. 1000 hPa: 18C)

> layer 1

2. 900 hPa: 20C)

> layer 2

3. 800 hPa: 8C)

> layer 3

4. 700 hPa: -2C )

> layer 4

5. 600 hPa: -9C )

> layer 5

6. 500 hPa: -20C)

>layer 6

7. 400 hPa: -40C)

> layer 7

8. 300 hPa: -40C

10 0 10 20 30

Layer 1: stable for dry air


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1000

900

800

700

600

500

400

300

-10 0 10 20 30

0 10 20 30

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6

Layer 7

stable for saturated air

absolute stableLayer 2: unstable for dry air

unstable for saturated air

absolute unstableLayer 3: indifferent for dry air



indifferent for saturated air



conditional stableLayer 6: unstable for dry air


absolute unstableLayer 7: stable for dry air

stable for saturated air

absolute stable

DE TSK VERLOOPT STABIEL VOOR DROOG- EN


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DE TSK VERLOOPT STABIEL VOOR DROOG- EN

NATADIABATISCHE PROCESSEN:ABSOLUUT STABIEL

S

U

M

M

A

R

Y

Blz

2-15

DE TSK VERLOOPT ONSTABIEL VOOR DROOG- EN


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DE TSK VERLOOPT ONSTABIEL VOOR DROOG- EN

NATADIABATISCHE PROCESSEN:ABSOLUUT ONSTABIEL

DE TSK VERLOOPT STABIEL VOOR EEN DROOG- MAAR


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DE TSK VERLOOPT STABIEL VOOR EEN DROOG-, MAAR

ONSTABIEL VOOR EEN NATADIABATSCICH PROCES:

VOORWAARDELIJK (ON)STABIEL


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Potential instability fig.:2.18Temp:

Onderin nat.

Bovenin droog

Td T


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Potential instability

In layered clouds EMBD (Embedded) CBs
http://annettekapoen.punt.nl/upload/weer/zon_1.gifhttp://www.astro.uu.nl/~strous/AA/pic/maan08.jpg


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Changing stability by

1) Diurnal variation of Temperature

T10 13 15 19

ELR

WAA

No advection

h

2) Advection* of Warm or Cold

air

FRICTION INVERSION
http://annettekapoen.punt.nl/upload/weer/zon_1.gifhttp://www.astro.uu.nl/~strous/AA/pic/maan08.jpg


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3) Turbulence (=mixing)

Changing stability by

4) Vertical movement by Divergence orConvergence

inversion Wind

ELR-

TSK

FRICTION-INVERSION

T

DALR

S bid I i


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Subidence Inversion

SAMENDRUKKEN VAN EEN LUCHTLAAG TIJDENS


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SAMENDRUKKEN VAN EEN LUCHTLAAG TIJDENS

SUBSIDENTIE

Section2 TB Meteo

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