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|Lesson Plan. |
Teacher: Okropiridze T.
Specific Topic: Solar Radiation.
Goal: Wake up the students’ awareness about the importance of solar energy for the Earth. Broaden the students’ mind about the Sun’s light as an alternative source of energy.
1. Students will get knowledge about the importance of solar energy.
2. Students will improve speaking and writing skills on the offered topic to use new vocabulary in their answers.
3. Students will demonstrate the addition of new terms while speaking.
4. Students will create mini posters for use in later activities.
1. Sheets with the text “ Solar Energy”
2. Cards with tasks.
3. Paper and markers.
1. Smart Board.
To work over the text .The teacher comments some information while showing some schemes on the smart board.
Life would be impossible without Sun's light. Energy received as solar radiation drives all life and meteorological processes on Earth. Like the hand that winds the spring of a clock, directly or indirectly, the Sun provides the external energy supporting the life activities within all ecosystems. Practically all the fuels that modern society uses - gas, oil, and coal - are stored forms of energy received from the Sun as electromagnetic radiation millions of years ago. Only the energy from nuclear reactors does not originate from the Sun.
Solar Constant: 1367 W/m2
Teacher: Solar constant is the total radiation energy received from the Sun per unit of time per unit of area on a theoretical surface perpendicular to the Sun's rays and at the Earth's mean distance from the Sun. Due to the Earth rotation, the incoming flux of solar energy falling onto the Earth's cross-section is distributed across the entire globe.
The energy flux reaching the outer atmosphere of the Earth is called the solar constant. Solar radiation has been increasing steadily and now it is by 30% more than it was 3.8 billion years ago when life on Earth just emerged. At present, solar constant is about 1367 W/m2. More precisely, Is = (1367 ± 3) W/m2 where Is is the solar constant. Because the Earth has four times as much area as a flat disk of equivalent radius, the average solar flux incident on the top of the atmosphere is 1/4 solar constant.
Earth's planetary albedo is defined as the fraction of the total incident solar radiation reflected by a planet back to space. At present albedo of the Earth is equal to 30% (=25% is the reflection of clouds and airborne particles of the atmosphere, and -5% is the reflection of the Earth's surface).
Thus, 1/4 Is (1 ~ A) = 240 W/m2 is the averaged flux of the solar radiation per unit of the Earth's surface, where A = 0.3 - is the planetary albedo.
Clouds, dust, water vapor, and gases of the atmosphere absorb about half the solar radiation that might otherwise reach the Earth.
Eventually, 150 W/m2 is the flux of the solar radiation that reaches the Earth's surface.
The Sun is a thermonuclear reactor. Energy is released in the form of electromagnetic waves of a wide range. These extend from . X-rays of very short wavelength to radio waves of very long wavelength, but almost all Sun's radiation falls within the ultraviolet, visible, and infrared radiation bands.] Nearly half of solar energy occurs in the visible part of the solar spectrum between 400nm and 700nm, about 25% - in the ultraviolet band, and the remaining solar energy occurs at near infrared wavelength, mostly from 700nm to 4000nm (1 nm = 10 ~ 9 m: one nanometer equals ten to the minus ninth power meters or one billionth of a meter).
Water vapor, CO2, and other “greenhouse gases”
Troposphere Infrared (Heat) Radiation
Teacher: The greenhouse effect. Atmosphere, like glass in a greenhouse, prevents infrared radiation escape.
The near-ultraviolet radiation from the Sun produces the ozone (O3) layer, which in turn shields the Earth from such radiation. Almost all ultraviolet radiation is absorbed by the ozone layer and oxygen. This is vitally important for living things because ultra-violet is extremely harmful and potentially lethal to most forms of life.
The atmosphere is almost perfectly transparent to incoming radiation of the visible band. The Earth reradiates this energy as infrared (heat), waves. Water vapor, carbon dioxide (CO2), nitrous oxide (N2O), ozone (O3), and some other gases absorb infrared wavelengths, much of which gets reradiated back toward the Earth (see Fig. 6). The atmosphere therefore behaves like glass in a greenhouse, allowing passage of light rather than heat. This phenomenon is termed the "greenhouse effect". If the Earth had no atmosphere (but the same reflectivity to solar radiation, or albedo, as it has now), its average surface temperature would be -18°C instead of comfortable +15°C found today. Thus, the result of greenhouse effect is a net warming of the earth-atmosphere system and of the Earth surface temperature.
The first law of thermodynamics states that when energy of one form disappears, an equivalent amount of energy appears in some other form. It means that, in any case, light energy can be neither created nor destroyed as it passes through the atmosphere. It may, however, be transformed into equivalent amount of another type of energy, such as biochemical energy, energy of motion (kinetic energy), or heat.
According to the second law of thermodynamics the efficiency of any energy transformation is never "perfect": when energy changes from one form to another, some of the energy is lost to the system as "useless" heat.
The laws of thermodynamics hold for all energy transformations, including those involving the biochemical energy of life. In accordance with these laws, the earth-atmosphere system balances absorption of short-wave solar radiation by emission of long-wave infrared (heat) radiation to space.
To work over the tasks printed on the cards.
a)Review questions: ( Speaking)
1) What is the source of energy supporting all life and meteorological processes?
2) What is the energy flux: a) entering the outer atmosphere; b) reaching the Earth's surface?
3) Why doesn't all energy radiated by the Sun reach the Earth's surface?
4) What part of the Sun's radiation falls in the visible band of the solar spectrum?
5) What happens to the ultraviolet portion of solar radiation when it passes through the atmosphere?
6) To what radiation is the atmosphere more transparent: to the visible sunlight or to heat (infrared) radiation?
7) What would the average Earth's surface temperature be if there were no greenhouse effect?
8) Why do we call the first law of thermodynamics the law of energy conservation?
b) Translate into English:
a) формы жизни - e) источники энергии-
b) потоки энергии- | f) длина волны-
c) ВОДЯНОЙ ПАР- g) диапазон излучения-
d) круговорот вещества- h) отраженное излучение-
Translate the phrases and use them in the sentences of your own:
a) life under certain the top of the atmosphere
b) pass through the atmosphere conditions
c) on the top of the atmosphere
d) transformed into thermal radiation
e) by clouds and airborne particles
f) back into space
g) from X-rays to radio waves spectrum
h) in the visible part of the
i) according to the law
j) average surface
k) absorbed by the ozone layer temperature
l) transparent to incoming radiation
m) without sunlight
Look at figure and answer the questions:
Near Infar (IR)
Short-wavelength, (high- energy quanta)
5 700ml 10ml
Teacher : Spectrum of electromagnetic radiation. The Sun emits most of its energy between 200 and 4000 nm, primarily in the ultraviolet (UV), visible, and near-infrared (IR) wavelength regions.
1) What colors give the white color when mixed?
2) Is it correct: the shorter the radiation wavelength the higher its quanta energy?
3) What is the wavelength band of the visible light (in meters and nanometers)?
4) What is the wavelength range in which the Earth releases the energy?
5) Which light has a longer wavelength - green, red or violet?
The students are divided in two groups.
Task for each group :
1. to ask the students to draw an object or device which can be used as an alternative source of solar energy on a poster.
2. to ask the students to explain where and how the drawn object can work.
3. to ask the students to clarify how the drawn object can be used in the town where they live in.
(This is a town where there are 4 coal mines.)
Teacher: Renewable energy technology is now ready to be used and will meet the world’s energy demand by 2030 People will find new energy sources like wind and solar power that won’t pollute and will never run out. They are also less expensive compared to other sources of energy.
Task: Write an essay on “How can new energy sources help in the future?”
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