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Solar energy
The document provides a comprehensive overview of solar energy and the characteristics of the sun, including its size, composition, and structural layers such as the core, photosphere, and corona. It details the processes of nuclear fusion in the sun, the formation of solar phenomena like sunspots and prominences, and the implications of the solar wind. Additionally, the document describes the solar spectrum and how solar energy impacts life on Earth.
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Solar energy
- 1. SOLAR ENERGY By Dr. SonalG. Chonde Department of Environmental Science, Shivaji University, Kolhapur.
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- 3. The Sun isthe star at the center of the solar system. It has a diameter of about 1,392,000 km, about 109 times that of earth and its mass (about 2 × 1030 kilograms, 330,000 times that of Earth) accounts for about 99.86% of the total mass of the Solar System. Figure : sun observe by SUMER instrument
- 4. Physical characteristics Mean diameter 1.392×106 km 109 × Earth Equatorial radius 6.955×105 km 109 × Earth Equatorial circumference 4.379×106 km 109 × Earth Surface area 6.0877×1012 km2 11,990 × Earth Volume 1.412×1018 km3 1,300,000 × Earth Mass 1.9891×1030 kg 333,000 × Earth Average Density 1.408×103 kg/m3
- 5. Hydrogen 73.46% HELIUM 24.85% OXYGEN 0.77% CARBON 0.29% IRON .16% SULFER 0.12% NEON 0.12% NITROGEN 0.09% SILICON 0.07% MAGNESIUM 0.05%
- 6. As theSun consists of a plasma and is not solid, it rotates faster at its equator than at its poles. This behavior is known as differential rotation, and is caused by convection in the Sun and the movement of mass, due to steep temperature gradient from the core outwards. The period of this actual rotation is approximately 25.6 days at the equator and 33.5 days at the poles. The Sun does not have a definite boundary as rocky planets do, and in its outer parts the density of its gases drops exponentially with increasing distance from its center. The solar interior is not directly observable, and the Sun itself is opaque to electromagnetic radiation.
- 9. The core ofthe Sun is considered to extend from the center to about 0.2 to 0.25 of the solar radius. It has a density of up to 150 g/cm3 (about 150 times the density of water) and a temperature of close to 13.6 million Kelvin(K). By contrast, the Sun's surface temperature is approximately 5,800 K. The core is the only region in the Sun that produces an appreciable amount of thermal energy through fusion
- 12. From about 0.25to about 0.7 solar radii, solar material is hot and dense enough that thermal radiation is sufficient to transfer the intense heat of the core outward.This zone is free of thermal convection while the material gets cooler from 7 to about 2 million Kelvin with increasing altitude, this temperature gradients less than the value of the adiabatic lapse rate and hence cannot drive convection. Energy is transferred by radiation ion of hydrogen and helium emit photons , which travel only a brief distance before being reabsorbed by other ions.
- 13. An theSun's outer layer, from its surface down to approximately 200,000 km (or 70% of the solar radius), the solar plasma is not dense enough or hot enough to transfer the thermal energy of the interior outward through radiation; in other words it is opaque enough. As a result, thermal convection occurs as thermal columns carry hot material to the surface (photosphere) of the Sun. Once the material cools off at the surface, it plunges downward to the base of the convection zone, to receive more heat from the top of the radiative zone. At the visible surface of the Sun, the temperature has dropped to 5,700 K and the density to only 0.2 g/m3 (about 1/6,000th the density of air at sea level) The thermal columns in the convection zone form an imprint on the surface of the Sun as the solar granulation and super granulation The turbulent convection of this outer part of the solar interior causes a "small-scale" dynamo that produces magnetic north and south poles all over the surface of the Sun
- 14. The Sun'sphotosphere has a temperature between 4500 and 6000 Kelvin (with an effective temperature of 5800 Kelvin) and a density of about 2 × 10−4 Kg m3 other stars may have hotter or cooler photospheres. The Sun's photosphere is composed of convection cell called granules — cells of gas each approximately 1000 kilometers in diameter with hot rising gas in the center and cooler gas falling in the narrow spaces between them. Each granule has a lifespan of only about eight minutes, resulting in a continually shifting "boiling" pattern. Grouping the typical granules are super granules up to 30,000 kilometers in diameter with lifespan of up to 24 hours. These details are too fine to see on other stars.
- 15. The chromospheres(literally, "color sphere") is a thin layer of the Sun's atmosphere just above the photosphere , roughly 2,000 kilometers deep. The chromospheres is more visually transparent than the photosphere. The name comes from the fact that it has a reddish color, as the visual spectrum of the chromospheres is dominated by the deep red H-alpha spectral line of hydrogen. The coloration may be seen directly with the naked eye only during a total solar eclipse , where the chromospheres is briefly visible as a flash of color just as the visible edge of the photosphere disappears behind the Moon . the temperature of the chromospheres is hotter than that of the photosphere. The photosphere is closer to the center of the sun and its temperature is around 4000 K to 6400 K but the chromospheres is about 4500 K to as high as 20,000 K Figure :The Sun observed through a telescope with an H-alpha filter
- 16. A coronais a type of plasma “atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total Solar eclipse, but also observable in a Chronograph. The Latin root of the word corona means crown. The high temperature of the corona gives it unusual spectral features. Light from the corona comes from three primary sources, which are called by different names although all of them share the same volume of space. The K-corona (K for kontinuierlich, "continuous" in German) is created by sunlight scattering off free electron The F-corona (F for Fraunhofer) is created by sunlight bouncing off dust particles The E-corona (E for emission) is due to spectral emission lines produced by ions that are present in the coronal plasma Figure : During a total solar eclipse , the solar corona can be seen with the naked eye.
- 17. Sunspots are temporaryphenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. they are caused by intense magnetic activity, temperatures of sunspot are roughly 3,000–4,500 K the contrast with the surrounding material at about 5,780 K leaves them clearly visible as dark spots, as the intensity of a heated black body . They may also travel at relative speeds ("proper motions") of a few hundred m/s when they first emerge onto the solar photosphere.
- 18. Granules on thephotosphere of the sun are caused by convection current of plasma within the Sun's convective zone. The grainy appearance of the solar photosphere is produced by the tops of these convective cells and is called granulation. The rising part of the granules is located in the center where the plasma is hotter. The outer edge of the granules is darker due to the cooler descending plasma. A typical granule has a diameter on the order of 1,000 kilometers and lasts 8 to 20 minutes before dissipating. Below the photosphere is a layer of “super granules" up to 30,000 kilometers in diameter with lifespan of up to 24 hours.
- 19. A prominence isa large, bright feature extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's corona. While the corona consists of extremely hot ionized gases, known as plasma, which do not emit much visible light, prominences contain much cooler plasma, similar in composition to that of the chromospheres. A typical prominence extends over many thousands of kilometers. roughly half the radius of the Sun or 28 times the diameter of the Earth. Flocculi (plural of flocculus) is another term for these filaments, and dark Flocculi typically describes the appearance of solar prominences when viewed against the solar disk in certain wavelengths. Solar prominences.
- 20. The solar windis a stream of charged particle ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 10 and 100 keV. The stream of particles varies in temperature and speed over time. These particles can escape the Sun's gravity because of their high kinetic energy and the high temperature of the corona The solar wind creates the heliosphere a vast bubble in the interstellar medium that surrounds the solar system. The solar wind is divided into two components, respectively termed the slow solar wind and the fast solar wind. The wind is considered responsible for the tails of comets, along with the Sun's radiation. Earth itself is largely protected from the solar wind by its magnetic field ,which deflects most of the charged particles, however some of the charged particles are trapped in the Van Allen radiation belt.
- 21. Birth: Gravitational Collapse of InterstellarCloud "Hayashi Contraction" of Protostar Life: Stability on Main- Sequence Long life - energy from nuclear reactions in the core (E = mc2) Death: Lack of fuel, instability, variability expansion (red giant, then white dwarf) Life Cycle of the Sun
- 22. Solar spectrum: Thesolar radiation distribution constituting UV-VIS-IR radiation. solar wide spectrum of wavelengths The maximum span of solar spectrum: The region of spectrum where a high energy radiation is falling on earth (1.4-1.8 eV)
- 23. BLUE GREEN YELLOW ORANGE RED VIOLET Increasing λ Cosmic and γ-rays X-rays (UV) Vacuum ultraviolet (UV) Near ultraviolet Visible (NIR) Near infrared (IR) Infrared Radio Microwave 0.1 nm200 nm 400 nm 800 nm 2 μm 50 μm 1019Hz 1015Hz 1013Hz Increasing Frequency (ν)
- 24. The surface receivesabout 47% of the total solar energy that reaches the Earth. Only this amount is usable.
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- 28. Complete the Reaction 1H 4Be 1 H 8O 4Be 2He 2He 1H 2He 2He 2He 6C 1Helement atomic number (protons) 6C
- 29. Nuclear Fusionis the energy-producing process taking place in the core of the Sun and stars The core temperature of the Sun is about 15 million °C. At these temperatures hydrogen nuclei fuse to give Helium and Energy. The energy sustains life on Earth via sunlight
- 30. 1kg Hydrogen .993 kgHelium
- 31. Neutron induced inU235 Fission is Exothermic The sum of the masses of the resulting nuclei is less than the original mass (about 0.1% less) The “missing mass” is converted to energy according to E=mc2
- 32. Review Nuclear fission: A largenucleus splits into several small nuclei when impacted by a neutron, and energy is released in this process Nuclear fusion: Several small nuclei fuse together and release energy.
- 33. It is anartificial constructed pond. It consist of different layers of water Temperature as well as salt concentration goes on increasing as we move from top to bottom of solar pond. 1) Surface convective Zone 2) Non- Convective Zone 3) Lower convective Zone
- 47. 1) LatentHeat Storage Device :- Storage of Thermal energy by Phage Changing Material (PCM) such a material which changes phase when it store energy content. E.g.. Hydrated salts 2) Sensible Heat Storage Device :- Storage of Thermal energy by absorbing it. E.g.. Solar pond