Презентация Solar Radiation онлайн

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Тип файла:

ppt / pptx (powerpoint)
Всего слайдов:

28 слайдов
Для класса:

1,2,3,4,5,6,7,8,9,10,11
Размер файла:

2.77 MB
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68
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Слайды и текст к этой презентации:

№1 слайд

Содержание слайда: Solar Radiation The energy emitted by the Sun is called SOLAR RADIATION. It is the only source of energy for the Earth. Other sources: Earth’s surface – 5000 times less, Stars – 30.000.000 times less. When arriving to Earth, the larger part of the solar radiation (SR) transforms to heat energy, and a small portion of it to electric energy (upper atmosphere). area receives annually of energy

№2 слайд

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№3 слайд

Содержание слайда: Energetic state of a body Any body the temperature of which is above 0 K radiates energy. Equilibrium state Non-equilibrium state

№4 слайд

Содержание слайда: Units and notions The unit of radiant energy is Joule (J) or kJ, mJ, hJ. The basic characteristics of radiation is FLUX of RADIANT ENERGY. Amount of energy emitted (or passing) through the unit of area in a unit of time is termed SURFACE DENSITY of RADIATION FLUX or RADIOSITY. It is also called simply Radiant flux or Flux of radiation. Units:

№5 слайд

Содержание слайда: Wave nature of the radiant flux Radiant energy spreads in form of waves of different length. Distribution of energy in wavelength is very important characteristics. Let’s take wavelength interval from λ to dλ i.e. dλ. Amount of energy emitted trough the body surface ds is proportional to ds and dλ denotes monochromatic (homogeneous) flux of radiation. It represents the quantity to characterize the wavelength around λ. It is also called spectral density of radiation flux or emitting capability of the body or simply emittance.

№6 слайд

Содержание слайда:

№7 слайд

Содержание слайда: Absorption, reflection, transmission As a monochromatic flux of radiation falls on a body and passing through it, the flux is partly absorbed, partly reflected, and the remaining part is allowed for transmission. Absorption capability of the body (relative coefficient of absorption). Reflection capability of the body (albedo). Relative coefficient of transmission. These coefficients depend on wavelength and properties of the body (Selectivity of the body)

№8 слайд

Содержание слайда: Special properties of bodies Absolutely Black body (Bb)

№9 слайд

Содержание слайда: Transmission function for the atmosphere The atmosphere is a transparent body. Meteorologists usually deal with some layers of it. Monochromatic entering flux Outgoing flux

№10 слайд

Содержание слайда: Kirchhoff’s law There is a good relation between absorption and emittance of a body. The ratio Em/Ab does not depend on the nature of the body. It is the same function B(λ,T) for every of bodies. That’s Kirchhoff’s law. For a Bb In the nature there are no absolutely black bodies. Any real body emits and absorbs less energy of the same wavelength than Bb. However it emits and absorbs energy of the same wavelength. M. Plank’s formula

№11 слайд

Содержание слайда: Gustav Robert Kirchhoff Wilhelm Wien 1824 –1887 Born Königsberg, Kingdom of Prussia He coined the term "black body" radiation in 1862

№12 слайд

Содержание слайда: Max Planck 1858 –1947 Planck was gifted when it came to music. He took singing lessons and played piano, organ and cello(Violoncello ), and composed songs and operas. However, instead of music he chose to study physics.

№13 слайд

Содержание слайда: 1-st Wien’s law (Displacement law) Distribution of energy in an absolute Bb radiation spectrum is not homogeneous. It depends on the body temperature. Suppose: There is one wavelength (λm) where radiant energy is maximal. The λm value depends on the body temperature. The lower the temperature, the larger the λm value.

№14 слайд

Содержание слайда: Practical application of the 1 Wien’s law?

№15 слайд

Содержание слайда: Much of a person's energy is radiated away in the form of infrared light. Some materials are transparent in the infrared, while opaque to visible light, as is the plastic bag in this infrared image (bottom). Other materials are transparent to visible light, while opaque or reflective in the infrared, noticeable by darkness of the man's glasses.

№16 слайд

Содержание слайда: Temperatures of flames by appearance The temperature of flames with carbon particles emitting light can be assessed by their color: Red Just visible: 525 °C (980 °F) Dull: 700 °C (1,300 °F) Cherry, dull: 800 °C (1,500 °F) Cherry, full: 900 °C (1,700 °F) Cherry, clear: 1,000 °C (1,800 °F) Orange Deep: 1,100 °C (2,000 °F) Clear: 1,200 °C (2,200 °F) White Whitish: 1,300 °C (2,400 °F) Bright: 1,400 °C (2,600 °F) Dazzling: 1,500 °C (2,700 °F) http://en.wikipedia.org/wiki/Fire#Typical_temperatures_of_fires_and_flames

№17 слайд

Содержание слайда: Some interesting results gained from the 1-st Wien’s law

№18 слайд

Содержание слайда: The total flux and 2-nd Wien’s law The total flux of Bb radiation includes energy of all wavelengths emitted by the body. After integration 2-nd Wien’s law

№19 слайд

Содержание слайда: Grey body Since in the nature there are no absolutely black bodies, we may call all of them grey bodies. The grey body is a body the absorption capability of which is the same for every wavelength. Radiation flux of any grey body can be presented as;

№20 слайд

Содержание слайда: Extinction and Bouguer’s law Notion of extinction The term extinction means weakening of the radiation energy as its flux passing through a body (or atmospheric layer). Extinction=absorption + diffusion Bouguer’s law holds: the flux of radiation is extinguished proportionally to its intensity (Fλ), density of the medium it passes through (ρ), and the passing distance (dl). is mass extinction index, its dimension is

№21 слайд