Solar Energy"We live in the glow of a star
named Sol,
and we call it Solar Energy." Near the equator, at the outer atmosphere, our planet receives from the Sun about 1360 joules of energy per second over every square metre. That's 1.36 kilowatts of power per square metre. On a clear day, at the Earth's surface, we are receiving about 1 kilowatt per square metre (1kW/m2), or just over one horsepower per square yard. For most of our history we have assumed that the Earth
we stood upon was the center of the Universe. It is only in the last 400 years
that we have gradually learned where we are in Space. Even now, most of us
are used to thinking of the Sun as moving across our sky as the Earth stands
still. Think of the horses of the Sun, pulling a thundering chariot. For a good compilation of Sun legends from around the World, visit: ******* Because our planet is spinning off-tilt (by 23-1/2 degrees) to its path around the Sun, and because our orbit around the Sun is also elliptical, different parts of the Earth's surface receive varying amounts of radiant energy throughout our days and year. These differences in energy are evident each day as morning, noon, and night; and throughout the year as our Seasons. Each time we circle the sun, we repeat the cycle of seasonal life. Plants absorb solar energy in a remarkable process called "making with light" - photosynthesis. Plants, bravely growing out from the sides of the planet, away from Earth's gravity field, intercept solar energy with their leaves, and make themselves mostly out of water and carbon dioxide. We and other beings live on the vegetation produced.....that vegetation, "stored" solar energy, is our only source of energy. In the oceans phytoplankton are the base of marine life. "Like their land-based relatives, phytoplankton require sunlight, water, and nutrients for growth. Because sunlight is most abundant at and near the sea surface, phytoplankton remain at or near the surface. Also like terrestrial plants, phytoplankton contain the pigment chlorophyll, which gives them their greenish color. Chlorophyll is used by plants for photosynthesis, in which sunlight is used as an energy source to fuse water molecules and carbon dioxide into carbohydrates—plant food. Phytoplankton (and land plants) use carbohydrates as "building blocks" to grow; fish and humans consume plants to get these same carbohydrates." - What are Phytoplankton? by David Herring, at NASA's Earth Observatory site. We are SolarDriven.
For an excellent treatment of this by an Agriculural College, please see "The Earth as a Solar Driven System". Our thin layer of atmospheric gases deflects and scatters to some extent direct solar radiant energy. Water vapour clouds reflect some of it. Nevertheless, as each part of the planet turns toward the Sun, on a 'sunny' day roughly 800 -1000 watts of power per square metre are received at ground [1 horsepower = 746 watts] for many hours at a time. This warms the surface of our planet, mostly ocean, and ocean and air currents transport that warmth from the equator to the poles. At each point on the planet's surface solar energy taken on during the day is re-radiated into Space at night. That turned surface of planet is now warmer that anything in Space surrounding it, and must necessarily radiate away its heat. "The coldest hour is just before the dawn". Turning into the Sun's radiation each morning we again take on more solar energy. The Sun is always shining, and the Earth is always spinning. Constantly, half of the Earth is receiving direct solar radiation, and half is facing into Space and radiating energy away. As long as there is a balance of energy received on dayside, and energy radiated away nightside, we don't have global warming. Concerns about climate change arise because pollution from our combustion activites is changing the composition of the gases in our atmosphere. Some of these new and/or increased gases absorb the out-going infra-red radiation, keeping that energy in our atmosphere, from where it can re-emit to Earth. During the night we are getting a small back-glow of radiant energy from those gases. Right now our planet's surface temperature (including atmospheric and ocean temperature) is rising. Higher temperatures and changing rainfall patterns will affect plants. There's also concern about a spreading of tropical diseases and insects to places further North. These are vast changes we have intitiated, mostly by being the number of us that we are, burning fossil fuels. Earth and Moon ******* NASA's "Blue Marble" pictures of our Planet. "This spectacular “blue marble” image is the most detailed true-color
image of the entire Earth to date. Using a collection of satellite-based
observations, scientists and visualizers stitched together months of observations
of the land surface, oceans, sea ice, and clouds into a seamless, true-color
mosaic of every square kilometer (.386 square mile) of our planet. These
images are freely available to educators, scientists, museums, and the public."
Back here, on a human scale, we can use the Sun's energy directly to cook food, purify water, heat water and air, and warm (or cool!) our buildings. Further, we can produce electricity, with photovoltaic panels. We, as human beings, at our temperature, emit radiation in the lower "infra-red" range. Our temperature is about 300 Kelvin. Our Sun is emitting energy at the predominant 'wavelengths' it does because its outer gases are around 5800 Kelvin in temperature. Although gravity-driven nuclear fusion reactions deep in the Sun's core provide the energy for heating its outer gases, "solar energy" as received by us is the electromagnetic energy (light) radiating from the glowing gases at the Sun's outer layer. Electromagnetic Radiation,
Temperature, Colour, Light "Adjust the temperature of the nuclear-powered blow torch and see
how the spectrum of the robot changes as you increase the temperature. Observe
where the peak wavelength is at each temperature." Visit the Nine Planets Web site to gather facts about the Sun and Earth. For images of the planets, see the Solar System Simulator at NASA
From
Sun to Earth Solar radiation peaks in the visible light range (blue) and tapers off into the infra-red. Over 40% of the sun's electromagnetic energy is something we can see...we call it light. The different colours we see are the result of different wavelengths of light energy reacting with the biochemistry of our eyes. It is a difficult thought to grasp, but true, that colors don’t exist except in our minds. Outside of us, “yellow” and “green” don’t exist...just different wavelengths of radiant energy. Because the electromagnetic spectrum is so vast, and the visible band-width such a small part of the electromagnetic spectrum, the error has often been made that visible light can only be a small part of solar energy (perhaps 5% at most) and that solar energy is some mysterious wavelength energy. In reality, almost all of solar energy is what we've always perceived as light and heat. Depending on what wavelengths are agreed upon as “visible light”, about 42% of the sun’s energy is in our visible light range. About 6-7% is in the ultra-violet (ultra = beyond; "beyond"-violet) range. Most of this is shielded by the ozone layer. The rest (just over 50%) we call near infra-red (infra = below; "below"-red). We perceive infra-red radiation as heat. Electromagnetic radiation of these wavelengths, between 200 and 4000 nanometers, account for 99% of Solar Energy. Remote
Sensing Solar Energy feeds All of Life on this Planet's surface. Solar Energy causes Winds and Ocean Currents. Guided Tour on Wind
Energy
Ocean Current
and Tidal Energy Solar Energy heats the world ocean.
The Sea is a natural collector of solar energy, and its floor is nutrient-rich (big fish eats little fishes, dies, and sinks to the bottom). Why not pump that water up, with electricity made from its temperature difference between bottom and top, and use the upwelling nutrients in sea-farms?
http://www.sunwindsolar.com |
