Super cooled water in the atmosphere and water

Содержание

1. Super cooled water in the atmosphere and water
2. Lecture 21Metastable stateIn some cases the relaxation
3. Lecture 21Super saturated water vapor or/and supercooled
4. Lecture 21Water droplet freezing processAt the temperature
5. Lecture 21Heterogeneous ice formation assumes existence of
6. Lecture 21DistillationSuppose there is a super cooled
7. Lecture 21Theory of distillationThe following equation set
8. Lecture 21Low Temperature Scanning Electron Microscope (LT-SEM) http://emu.arsusda.gov/snowsite/default.html
9. Lecture 21http://emu.arsusda.gov/snowsite/default.htmlhttp://emu.arsusda.gov/snowsite/default.html
10. Lecture 21http://emu.arsusda.gov/snowsite/default.htmlhttp://emu.arsusda.gov/snowsite/default.html
11. Lecture 21http://emu.arsusda.gov/snowsite/default.htmlhttp://emu.arsusda.gov/snowsite/default.html
12. Lecture 21Weather Sayings Mackerel sky and mares'
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Lecture 21Metastable stateIn some cases the relaxation time is rather long. It happens as the initial state is not really unstable. We say: “the system is in metastable state”.ABCA. Unstable stateB.

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Super cooled water in the atmosphere and water

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Слайд 1Lecture 21
Super cooled water in the atmosphere and water freezing
Stable

and unstable state of physical systems
Unstable state
Non-equilibrium state
Stable state
Equilibrium state
It

tends to be transferred into Stable (equilibrium) state

Equilibrium condition for a thermodynamic system

Minimal thermodynamic potential and maximal entropy

A closed thermodynamic system in unstable state after some time will come to

The time interval needed for a system to be transferred from unstable to stable state is called relaxation time

Lecture 21Super cooled water in the atmosphere and water freezingStable and unstable state of physical systemsUnstable stateNon-equilibrium

Слайд 2Lecture 21
Metastable state
In some cases the relaxation time is rather

long. It happens as the initial state is not really

unstable. We say: “the system is in metastable state”.

A. Unstable state

B. Metastable state

C. Stable state

Super saturated water vapor and super cooled water in the atmosphere are metastable thermodynamic systems.

To start condensation or freezing, some nuclei of the new state are needed

Lecture 21Metastable stateIn some cases the relaxation time is rather long. It happens as the initial state

Слайд 3Lecture 21
Super saturated water vapor or/and supercooled water droplets
Metastable state
No

condensation (crystallization) nuclei
The nuclei can appear due to density fluctuation

(random molecules approach each other)

Random molecular condensation (crystallization)

Energy released due to random condensation (crystallization), Er

Condensation (crystallization) on some larger nuclei releases additional energy EL.n.

Growth the nuclei requires some additional energy EN. It may come from condensation (crystallization)

Process will not go due to energetic disadvantage

There are condensation (crystallization) nuclei

Condensation will proceed, and the energy released will be scarified for formation of larger nuclei

Heterophased nuclei

Lecture 21Super saturated water vapor or/and supercooled water dropletsMetastable stateNo condensation (crystallization) nucleiThe nuclei can appear due

Слайд 4Lecture 21

Water droplet freezing process
At the temperature below 0°C, water

droplets may freeze becoming ice particles. For the ice phase

to appear a nucleus of the ice must be formed inside of the droplet.

Such process is called homogenous phase transfer

The new phase can appear on foreign body (heterogeneous nucleus). Such kind of bodies are called crystallization nuclei. Accordingly this process is called heterogeneous phase transfer

In the atmosphere both homogenous and heterogeneous phase transfer may take place

Lecture 21Water droplet freezing processAt the temperature below 0°C, water droplets may freeze becoming ice particles. For

Слайд 5Lecture 21
Heterogeneous ice formation assumes existence of special crystallization nuclei.

At present, meteorologists believe that condensation nuclei become (at least

partly) crystallization ones as the air temperature grows down below 0°C

Crystallization start

No crystallization

Crystallization nuclei are present.
Heterogeneous phase transfer

Crystallization nuclei are not present.

Homogenous phase transfer

It is believed that amount of crystallization nuclei in the atmosphere is rather small. Therefore, the major role in crystallization process is played the homogenous phase transfer. This conclusion is supported by the observed facts of super cooled water droplet clouds (T=-12…-20°C) existence for a long time.

Lecture 21Heterogeneous ice formation assumes existence of special crystallization nuclei. At present, meteorologists believe that condensation nuclei

Слайд 6Lecture 21
Distillation
Suppose there is a super cooled clouds consisting of

water drops and ice crystals

Initial time

W.V. sublimates on ice

crystal

Next time

Drops evaporate

And so on until all drops become evaporated. However this process is quite long, practically, it is infinite.

Lecture 21DistillationSuppose there is a super cooled clouds consisting of water drops and ice crystals Initial timeW.V.

Слайд 7Lecture 21
Theory of distillation
The following equation set is to be

solved to obtain unknown quantities r1 and r2 and a

at a given moment of time.

D denotes diffusion of the water molecules

Lecture 21Theory of distillationThe following equation set is to be solved to obtain unknown quantities r1 and

Слайд 8Lecture 21
Low Temperature Scanning Electron Microscope (LT-SEM)
http://emu.arsusda.gov/snowsite/default.html

Слайд 9Lecture 21
http://emu.arsusda.gov/snowsite/default.html
http://emu.arsusda.gov/snowsite/default.html

Слайд 10Lecture 21
http://emu.arsusda.gov/snowsite/default.html
http://emu.arsusda.gov/snowsite/default.html

Слайд 11Lecture 21
http://emu.arsusda.gov/snowsite/default.html
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Слайд 12Lecture 21
Weather Sayings

Mackerel sky and mares' tails make lofty ships

carry low sails.

Mackerel sky (cirrocumulus clouds) and mares' tails

(cirrus clouds, кобыльи хвосты) indicate that windy, stormy weather is coming.

Lecture 21Weather Sayings Mackerel sky and mares' tails make lofty ships carry low sails. Mackerel sky (cirrocumulus

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Super cooled water in the atmosphere and water

Содержание

Слайды и текст этой презентации

Слайд 1Lecture 21
Super cooled water in the atmosphere and water freezing
Stable

and unstable state of physical systems
Unstable state
Non-equilibrium state
Stable state
Equilibrium state
It

Слайд 2Lecture 21
Metastable state
In some cases the relaxation time is rather

long. It happens as the initial state is not really

Слайд 3Lecture 21
Super saturated water vapor or/and supercooled water droplets
Metastable state
No

condensation (crystallization) nuclei
The nuclei can appear due to density fluctuation

Слайд 4Lecture 21

Water droplet freezing process
At the temperature below 0°C, water

droplets may freeze becoming ice particles. For the ice phase

Слайд 5Lecture 21
Heterogeneous ice formation assumes existence of special crystallization nuclei.

At present, meteorologists believe that condensation nuclei become (at least

Слайд 6Lecture 21
Distillation
Suppose there is a super cooled clouds consisting of

water drops and ice crystals

Initial time

W.V. sublimates on ice

Слайд 7Lecture 21
Theory of distillation
The following equation set is to be

solved to obtain unknown quantities r1 and r2 and a

Слайд 8Lecture 21
Low Temperature Scanning Electron Microscope (LT-SEM)
http://emu.arsusda.gov/snowsite/default.html

Слайд 9Lecture 21
http://emu.arsusda.gov/snowsite/default.html
http://emu.arsusda.gov/snowsite/default.html

Слайд 10Lecture 21
http://emu.arsusda.gov/snowsite/default.html
http://emu.arsusda.gov/snowsite/default.html

Слайд 11Lecture 21
http://emu.arsusda.gov/snowsite/default.html
http://emu.arsusda.gov/snowsite/default.html

Слайд 12Lecture 21
Weather Sayings

Mackerel sky and mares' tails make lofty ships

carry low sails.

Mackerel sky (cirrocumulus clouds) and mares' tails

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Super cooled water in the atmosphere and water

Содержание

Слайды и текст этой презентации

Слайд 1Lecture 21Super cooled water in the atmosphere and water freezingStable

and unstable state of physical systemsUnstable stateNon-equilibrium stateStable stateEquilibrium stateIt

Слайд 2Lecture 21Metastable stateIn some cases the relaxation time is rather

long. It happens as the initial state is not really

Слайд 3Lecture 21Super saturated water vapor or/and supercooled water dropletsMetastable stateNo

condensation (crystallization) nucleiThe nuclei can appear due to density fluctuation

Слайд 4Lecture 21Water droplet freezing processAt the temperature below 0°C, water

droplets may freeze becoming ice particles. For the ice phase

Слайд 5Lecture 21Heterogeneous ice formation assumes existence of special crystallization nuclei.

At present, meteorologists believe that condensation nuclei become (at least

Слайд 6Lecture 21DistillationSuppose there is a super cooled clouds consisting of

water drops and ice crystals Initial timeW.V. sublimates on ice

Слайд 7Lecture 21Theory of distillationThe following equation set is to be

solved to obtain unknown quantities r1 and r2 and a

Слайд 8Lecture 21Low Temperature Scanning Electron Microscope (LT-SEM) http://emu.arsusda.gov/snowsite/default.html

Слайд 9Lecture 21http://emu.arsusda.gov/snowsite/default.htmlhttp://emu.arsusda.gov/snowsite/default.html

Слайд 10Lecture 21http://emu.arsusda.gov/snowsite/default.htmlhttp://emu.arsusda.gov/snowsite/default.html

Слайд 11Lecture 21http://emu.arsusda.gov/snowsite/default.htmlhttp://emu.arsusda.gov/snowsite/default.html

Слайд 12Lecture 21Weather Sayings Mackerel sky and mares' tails make lofty ships

carry low sails. Mackerel sky (cirrocumulus clouds) and mares' tails

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Слайд 1Lecture 21
Super cooled water in the atmosphere and water freezing
Stable

and unstable state of physical systems
Unstable state
Non-equilibrium state
Stable state
Equilibrium state
It

Слайд 2Lecture 21
Metastable state
In some cases the relaxation time is rather

Слайд 3Lecture 21
Super saturated water vapor or/and supercooled water droplets
Metastable state
No

condensation (crystallization) nuclei
The nuclei can appear due to density fluctuation

Слайд 4Lecture 21

Water droplet freezing process
At the temperature below 0°C, water

Слайд 5Lecture 21
Heterogeneous ice formation assumes existence of special crystallization nuclei.

Слайд 6Lecture 21
Distillation
Suppose there is a super cooled clouds consisting of

water drops and ice crystals

Initial time

W.V. sublimates on ice

Слайд 7Lecture 21
Theory of distillation
The following equation set is to be

Слайд 8Lecture 21
Low Temperature Scanning Electron Microscope (LT-SEM)
http://emu.arsusda.gov/snowsite/default.html

Слайд 9Lecture 21
http://emu.arsusda.gov/snowsite/default.html
http://emu.arsusda.gov/snowsite/default.html

Слайд 10Lecture 21
http://emu.arsusda.gov/snowsite/default.html
http://emu.arsusda.gov/snowsite/default.html

Слайд 11Lecture 21
http://emu.arsusda.gov/snowsite/default.html
http://emu.arsusda.gov/snowsite/default.html

Слайд 12Lecture 21
Weather Sayings

Mackerel sky and mares' tails make lofty ships

carry low sails.

Mackerel sky (cirrocumulus clouds) and mares' tails