Solar radiation extinction in the atmosphere

Сентябрь 3, 2022

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Solar radiation extinction in the atmosphere

Содержание

2. Incoming SR When passing through the atmosphere SR undergoes significant changes Incoming SR Diffused part of
3. Lecture 3 SR absorption The main gases absorbing S radiation are Ozone (O3), Oxygen (O2), Water
4. Lecture 3 Ozone (O3) absorbtion
5. Lecture 3 Oxygen Water vapor Carbon dioxide 0,13 – 0,24 0,72; 0,84; 0,94; 1,14; 1,38; 1,87;
6. Lecture 3 http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png
7. Lecture 3 Water vapor transmission function Qv is the mass of water vapor in a column
8. Lecture 3 SR diffusion in the atmosphere Terminology Diffusion (произвольное рассеяние) Scattering (Разбрасывание в разных направлениях
9. Lecture 3 Molecular scattering or Rayleigh scattering The atmosphere is turbid medium diffusing SR even in
10. Lecture 3 John William Strutt, third Baron Rayleigh "Lord Rayleigh - Biography". Nobelprize.org. 22 Sep 2010
11. Lecture 3 Rayleigh scattering http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c4
12. Lecture 3
13. Lecture 3 Raman scattering Rayleigh scattering can be considered to be elastic scattering ( the photon
14. Lecture 3 Raman scattering C. V. Raman discovered the inelastic scattering phenomenon which bears his name
15. Lecture 3 Molecular scattering (Continuation) The incident radiation flux of a definite wavelength makes fluxes of
16. Lecture 3 Multiple scattering Multiple scattering is the result of diffusion of the previously scattered radiation.
17. Lecture 3 Physical properties of the scattering fields The main characteristics of the properties is complex
18. Lecture 3 Aerosol scattering Mie theory (also called Lorenz–Mie theory or Lorenz–Mie–Debye theory) Aerosol particles are
19. Lecture 3 Gustav Mie, German physicist 1869 –1957
20. Lecture 3 The volume coefficient of extinction for larger particles is a function of quantity m
21. Lecture 3 If many particle of this size are present in the atmosphere the sky becomes
22. Lecture 3 http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c4 Scatter indicatrix is a vectoral diagram depicting dependence of scattered radiation on direction.
23. Lecture 3 Simultaneous molecular and aerosol scattering Since in the atmosphere some kind of aerosols always
24. Lecture 3 Optical depth of the atmosphere The volume extinction index summed up through the whole
25. Lecture 3 What is the type of scattering below? http://en.wikipedia.org/wiki/Rayleigh_scattering The beam of a 5 mW
26. Lecture 3 Which type of scattering is presented? Рерих Н.К. “Величайшая и Святейшая Тангла “
28. Скачать презентацию

Слайд 2

Incoming SR
When passing through the atmosphere SR undergoes significant changes
Incoming

Diffused part of SR

Absorbed part of SR

Слайд 3

Lecture 3
SR absorption
The main gases absorbing S radiation are Ozone (O3),

Oxygen (O2), Water vapor (H2O), and Carbon dioxide (CO2).
Ozone

Слайд 4

Lecture 3
Ozone (O3) absorbtion

Слайд 5

Lecture 3
Oxygen
Water vapor
Carbon dioxide
0,13 – 0,24
0,72; 0,84; 0,94; 1,14; 1,38; 1,87;

2,7; 3,2

1,44; 1,6; 2,02; 2,7; 4,31;

Слайд 6

Lecture 3
http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png
http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png

Слайд 7

Lecture 3
Water vapor transmission function
Qv is the mass of water vapor

in a column of air with the base 1
bi and βi are quantities empirically obtained.

Mass of the water vapor in the atmosphere is larger than that of ozone and carbon dioxide. Hence, it absorbs the larger part of the total absorbed radiation.

Nitrogen does not absorb radiation. Solid aerosols also absorb SR. In the layer 0,3 – 8,4 km O2 and CO2 absorb 3,8% and solid aerosols absorb 4,8% of SR.

Слайд 8

Lecture 3
SR diffusion in the atmosphere
Terminology
Diffusion (произвольное рассеяние)
Scattering (Разбрасывание в разных

направлениях любых веществ, предметов и даже людей)
Dispersion (синоним Scattering, в науке применяется к свету)
Turbidity (мутность).
The atmosphere is turbid medium due to many admixtures (aerosols) suspended in the air.
Aerosols scatter and absorb solar and terrestrial radiation.

Слайд 9

Lecture 3
Molecular scattering or Rayleigh scattering
The atmosphere is turbid medium diffusing SR

even in the absence of aerosols. In this case turbidity is molecular complexes.
The essence of the scattering is a particular form of interaction between variable field of coming electromagnetic waves and particles in the medium. Due to this kind of interaction the particles become sources of new electromagnetic waves.

Слайд 10

Lecture 3
John William Strutt, third Baron Rayleigh
"Lord Rayleigh - Biography". Nobelprize.org.

22 Sep 2010 http://nobelprize.org/nobel_prizes/physics/laureates/1904/strutt-bio.html

1842 - 1919

Слайд 11

Lecture 3
Rayleigh scattering
http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c4

Слайд 12

Lecture 3

Слайд 13

Lecture 3
Raman scattering
Rayleigh scattering can be considered to be elastic scattering

( the photon energies of the scattered photons is not changed)
Scattering in which the scattered photons have either a higher or lower photon energy is called Raman scattering.
Usually this kind of scattering involves exciting some vibrational mode of the molecules, giving a lower scattered photon energy, or scattering off an excited vibrational state of a molecule which adds its vibrational energy to the incident photon.

Слайд 14

Lecture 3
Raman scattering
C. V. Raman discovered the inelastic scattering phenomenon which

bears his name in 1928 and for it he was awarded the Nobel Prize for Physics in 1930.

Слайд 15

Lecture 3
Molecular scattering (Continuation)
The incident radiation flux of a definite wavelength makes

fluxes of the radiation of the same wavelength.
This process is greatly influenced by the geometrical structure and properties of the turbid medium. The geometrical structure is determined by dimensionless parameters and The laws of scattering are quite different for the
cases and .
If , the particles can be regarded as independent emittants.
The phenomenon of interference will not be observed.
No additional fields of radiation will appear.
Instead, the intensities of the radiation will be summed up. This simplifies solution of the problem of, so called, multiple scattering.

Слайд 16

Lecture 3
Multiple scattering
Multiple scattering is the result of diffusion of the

previously scattered radiation.

Multiple scattering can be neglected if the medium turbidity is not very high, i. e. the scattering particles are very distant from each other

Слайд 17

Lecture 3
Physical properties of the scattering fields
The main characteristics of the

properties is complex index of refraction.
is absolute index of refraction
is characteristics of absorption
The theory of the molecular scattering had been developed by English scientist Rayleigh, who put in the base of the theory the following assumptions:
All particles have form of a ball. They are dielectrically homogeneous and r<<λ.
Particle index of refraction does not markedly differ from that of the medium: nμ<1 and μ=2πr/λ.
The particles diffuse the light independently, I. e. L>>λ
The diffused light is observed at the distance R>>r

Слайд 18

Lecture 3
Aerosol scattering Mie theory (also called Lorenz–Mie theory or Lorenz–Mie–Debye theory)
Aerosol

particles are much larger than molecule complexes
There are two types of the larger particles in the atmosphere: non-transparent ones (dust, ), and transparent ones (water droplets).
Water droplets absorb radiation of ultraviolet and visible parts of the spectrum just slightly. Absolute index of refraction for water droplets varies not significantly. It average value n=1,33.
n is absolute index of refraction

Слайд 19

Lecture 3
Gustav Mie, German physicist
1869 –1957

Слайд 20

Lecture 3
The volume coefficient of extinction for larger particles
is a function

of quantity
m - complex index of refraction,
N is the number of particles in a unit of volume.
For very large particles (10In case r>40 μ, the scattering does not depend on wavelength.

Слайд 21

Lecture 3
If many particle of this size are present in the

atmosphere the sky becomes of whitish color (instead of light blue) due to the fact that the light dispersed in the same way regardless which wavelength is dispersed.
Due to the same reason, clouds and fogs have white (whitish) or gre`y color.
Scatter indicatrix for several values of parameter μ.

The larger particles mainly scatter in the direction of incident beam

Слайд 22

Lecture 3
http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c4
Scatter indicatrix is a vectoral diagram depicting dependence of scattered

radiation on direction.

http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c4

Слайд 23

Lecture 3
Simultaneous molecular and aerosol scattering
Since in the atmosphere some

kind of aerosols always exists, both molecular and aerosol scattering goes on simultaneously.
It makes difficult to estimate real scattering quantitatively from the theoretically obtained equations. Instead some empirical or semi-empirical relations are used for the purpose. It was learnt that regularities of the scattering strongly depends upon the sizes of the particles, and, first of all, on the water droplet sizes.
Very important characteristics is so called scattering index Kλ.

Molecular scattering index

Aerosol scattering index

Prevails up to 3 – 4 km

Prevails above 3 – 4 km

depends on turbidity

depend on turbidity too

Слайд 24

Lecture 3
Optical depth of the atmosphere
The volume extinction index summed up

through the whole atmosphere is termed optical depth of the atmosphere.

is the optical depth caused by molecular scattering, and is that caused by the total scattering.
In the ultraviolet area (λ<40μ) the molecular scattering makes the larger contribution in the total scattering, at λ=0,45 both contribution are almost equal, at λ>0,45 aerosol scattering contribution prevails.

Слайд 25

Lecture 3
What is the type of scattering below?
http://en.wikipedia.org/wiki/Rayleigh_scattering

The beam of

a 5 mW green laser pointer is visible at night due to Rayleigh scattering and airborne dust.

Слайд 26

Lecture 3
Which type of scattering is presented? Рерих Н.К. “Величайшая и Святейшая

Тангла “

Solar radiation extinction in the atmosphere

Содержание

Incoming SRWhen passing through the atmosphere SR undergoes significant changes Incoming

Lecture 3SR absorptionThe main gases absorbing S radiation are Ozone (O3),

Lecture 3Ozone (O3) absorbtion

Lecture 3OxygenWater vaporCarbon dioxide0,13 – 0,240,72; 0,84; 0,94; 1,14; 1,38; 1,87;

Lecture 3http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.pnghttp://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png

Lecture 3Water vapor transmission functionQv is the mass of water vapor

Lecture 3SR diffusion in the atmosphereTerminologyDiffusion (произвольное рассеяние)Scattering (Разбрасывание в разных

Lecture 3Molecular scattering or Rayleigh scatteringThe atmosphere is turbid medium diffusing SR

Lecture 3John William Strutt, third Baron Rayleigh"Lord Rayleigh - Biography". Nobelprize.org.

Lecture 3Rayleigh scatteringhttp://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c4

Lecture 3

Lecture 3Raman scatteringRayleigh scattering can be considered to be elastic scattering

Lecture 3Raman scatteringC. V. Raman discovered the inelastic scattering phenomenon which

Lecture 3Molecular scattering (Continuation)The incident radiation flux of a definite wavelength makes

Lecture 3Multiple scatteringMultiple scattering is the result of diffusion of the

Lecture 3Physical properties of the scattering fieldsThe main characteristics of the

Lecture 3Aerosol scattering Mie theory (also called Lorenz–Mie theory or Lorenz–Mie–Debye theory)Aerosol

Lecture 3Gustav Mie, German physicist1869 –1957

Lecture 3The volume coefficient of extinction for larger particlesis a function

Lecture 3If many particle of this size are present in the

Lecture 3http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c4Scatter indicatrix is a vectoral diagram depicting dependence of scattered

Lecture 3Simultaneous molecular and aerosol scattering Since in the atmosphere some

Lecture 3Optical depth of the atmosphereThe volume extinction index summed up

Lecture 3What is the type of scattering below?http://en.wikipedia.org/wiki/Rayleigh_scattering The beam of

Lecture 3Which type of scattering is presented? Рерих Н.К. “Величайшая и Святейшая

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