Clouds

Сентябрь 3, 2022

Содержание

2. Air temperature decrease is a reason for cloud formation
3. Advection Vertical motion
4. Water vapor content variation Eddy mixing Advection Divergence These factors act in case there is a
5. Classification of clouds Classification on visual appearance and structure Cumuliform(cauliflower) clouds Undulatiform(billow ) clouds Stratiform clouds
6. Classification based on altitude of the clouds 2 km 6 km Low level clouds Stratus, Stratocumulus
7. Cirrus felosus
8. Cirrus uncinus
9. Cirrostratus
10. Nimbostratus 2 km 6 km Ns As Rain Nimbostratus is the cloud that can be regarded
11. Altostratus
12. Nimbostratus
13. Chimney clouds Cu hum Cu med Cu cong Cb
14. Meso – scale convective complexes (MCC)
15. Chimney cloud formation Condensation level (LCL) zk Convection level (FCL) Three important levels: lifting condensation level
16. Lifting condensation level Determination of the lifting condensation level In case of adiabatic ascent Using Clausius
17. According to results of calculation dew point lapse rate in the conditions typical for the atmosphere
18. Free Convection level Lifting condensation level Free convection level
19. Level T=0°C determination Temperature variation within an ascending particle Temperature in the cloud 0°C
20. Entrainment Ascending particle (thermic) is not isolated. It exchanges mass, momentum, heat, moisture etc with ambient
21. According to measurements (with radar) For practical purposes we can adopt it as a constant. Parameter
22. Chimney clouds diurnal and annual variation Maximal occurrence between 9 a.m. and 7 p.m. Cu Cb
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Слайд 2

Air temperature decrease is a reason for cloud formation

Слайд 3

Advection
Vertical motion

Слайд 4

Water vapor content variation
Eddy mixing
Advection
Divergence
These factors act in case there is

a source of water to evaporate.

Слайд 5

Classification of clouds
Classification on visual appearance and structure
Cumuliform(cauliflower) clouds
Undulatiform(billow ) clouds
Stratiform

clouds

Слайд 6

Classification based on altitude of the clouds
2 km
6 km
Low level clouds
Stratus,

Stratocumulus

Middle level clouds

Altostratus

Altocumulus

Upper level clouds

Cirrus

Cirrostratus

Chimney clouds

Cumulonimbus
Cumulus congestus
Cumulus humbles

Слайд 7

Cirrus felosus

Слайд 8

Cirrus uncinus

Слайд 9

Cirrostratus

Слайд 10

Nimbostratus
2 km
6 km
Ns
As
Rain
Nimbostratus is the cloud that can be regarded both

middle and low level cloud.
Usually, it appears in combination with altostratus.

Слайд 11

Altostratus

Слайд 12

Nimbostratus

Слайд 13

Chimney clouds
Cu hum
Cu med
Cu cong
Cb

Слайд 14

Meso – scale convective complexes (MCC)

Слайд 15

Chimney cloud formation
Condensation level (LCL)
zk
Convection level (FCL)
Three important levels: lifting condensation

level (Zk) practically coincides with cloud bottoms, zero isotherm level (Z0) that separates super cooled (upper) part of the cloud water from non-super cooled (lower) one, free convection level (Zc) practically coincides with the cloud top.

0°C

Слайд 16

Lifting condensation level
Determination of the lifting condensation level
In case of adiabatic

ascent

Using Clausius Clapeyron equation

Слайд 17

According to results of calculation dew point lapse rate in the

conditions typical for the atmosphere in the extratropical latitudes, the value of this lapse rate can be adopted with the accuracy of 10% 0,17°/100m =const.

h. m.

An example

h. m.

Слайд 18

Free Convection level
Lifting condensation level
Free convection level

Слайд 19

Level T=0°C determination
Temperature variation within an ascending particle
Temperature in the cloud
0°C

Слайд 20

Entrainment
Ascending particle (thermic) is not isolated. It exchanges mass, momentum, heat,

moisture etc with ambient air

Ascending cloud air is (a) warmer, (b) saturated; ambient air is not saturated.

In the course of the exchange, the entrained air make the cloud air temperature lower ad drier. As result some droplets evaporate, that makes the temperature even more lower, and energy of instability decreases.

entrainment index

Слайд 21

According to measurements (with radar)
For practical purposes we can adopt it

as a constant.

Parameter is entrainment index

Since

only.

Слайд 22

Chimney clouds diurnal and annual variation
Maximal occurrence between 9 a.m. and

7 p.m.

Maximal development

Over planes

97% Cu

85% Cu

51% Cb

Over mountains

67% Cb

1-2 p.m.

Over planes and mountains

Over planes

2-4 p.m.

Over mountains

5-7 p.m.

Maximal occurrence (48%) is in summer, 17% - in autumn, 5% - in winter, and 30 % - in spring.

Clouds

Содержание

Air temperature decrease is a reason for cloud formation

AdvectionVertical motion

Water vapor content variationEddy mixingAdvectionDivergenceThese factors act in case there is

Classification of cloudsClassification on visual appearance and structureCumuliform(cauliflower) cloudsUndulatiform(billow ) cloudsStratiform

Classification based on altitude of the clouds2 km6 kmLow level cloudsStratus,

Cirrus felosus

Cirrus uncinus

Cirrostratus

Nimbostratus2 km6 kmNsAsRainNimbostratus is the cloud that can be regarded both

Altostratus

Nimbostratus

Chimney cloudsCu humCu medCu congCb

Meso – scale convective complexes (MCC)

Chimney cloud formationCondensation level (LCL)zkConvection level (FCL)Three important levels: lifting condensation

Lifting condensation levelDetermination of the lifting condensation levelIn case of adiabatic

According to results of calculation dew point lapse rate in the

Free Convection levelLifting condensation levelFree convection level

Level T=0°C determinationTemperature variation within an ascending particleTemperature in the cloud0°C

EntrainmentAscending particle (thermic) is not isolated. It exchanges mass, momentum, heat,

According to measurements (with radar)For practical purposes we can adopt it

Chimney clouds diurnal and annual variationMaximal occurrence between 9 a.m. and

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Advection
Vertical motion

Water vapor content variation
Eddy mixing
Advection
Divergence
These factors act in case there is

Classification of clouds
Classification on visual appearance and structure
Cumuliform(cauliflower) clouds
Undulatiform(billow ) clouds
Stratiform

Classification based on altitude of the clouds
2 km
6 km
Low level clouds
Stratus,

Nimbostratus
2 km
6 km
Ns
As
Rain
Nimbostratus is the cloud that can be regarded both

Chimney clouds
Cu hum
Cu med
Cu cong
Cb

Chimney cloud formation
Condensation level (LCL)
zk
Convection level (FCL)
Three important levels: lifting condensation

Lifting condensation level
Determination of the lifting condensation level
In case of adiabatic

Free Convection level
Lifting condensation level
Free convection level

Level T=0°C determination
Temperature variation within an ascending particle
Temperature in the cloud
0°C

Entrainment
Ascending particle (thermic) is not isolated. It exchanges mass, momentum, heat,

According to measurements (with radar)
For practical purposes we can adopt it

Chimney clouds diurnal and annual variation
Maximal occurrence between 9 a.m. and