Sunshine:
Besides atomic energy, volcanoes, earthquakes and tides, the energy emitted by solar energy and other stars is the total source of all energy on the earth.
Solar radiation energy reaching the upper limit of the earth's atmosphere is called astronomical solar radiation. When the earth is located at the average distance between the sun and the earth, the total energy of the whole spectrum of solar radiation received by the unit area where the upper boundary of the earth's atmosphere is perpendicular to the solar rays in unit time is called the solar constant. The common unit of solar constant is watt/square meter. Due to different observation methods and techniques, the obtained solar constant values are also different. The solar constant published by the World Meteorological Organization (WMO) at 198 1 is 1368 W/m2. If the sun constant is multiplied by the spherical area with the radius of the average distance between the sun and the earth, the total energy emitted by the sun per minute is about 2.273× 10? Coke. The heat radiated by the sun into space every second is equivalent to the sum of the heat generated by the complete combustion of 1 100 million tons of coal, which is equivalent to the power of a 520 trillion horsepower engine. Every square meter of the sun's surface is equivalent to a power station with 85,000 horsepower. ) and the earth only receives 2.2 billion of these energies. The energy that the sun sends to the earth every year is equivalent to 654.38+000 billion kWh.
Solar energy can be said to be inexhaustible, pollution-free, and is the most ideal energy source. More than 99% of the solar radiation spectrum in the upper atmosphere of the earth is between 0.15 and 4.0 microns. About 50% of solar radiation energy is in the visible spectrum (wavelength 0.4 ~ 0.76 micron), and 7% is in the ultraviolet spectrum (wavelength; 0.76 micron) and the maximum energy is at the wavelength of 0.475 micron. Because the wavelength of solar radiation is much smaller than that of ground and atmospheric radiation (about 3 ~ 120 micron), it is usually called short-wave radiation and long-wave radiation. Solar activity and changes in the distance between the sun and the earth will cause changes in the upper limit of solar radiation energy in the earth's atmosphere.
The sun has been transmitting light and heat to the earth. With sunlight, plants on the earth can carry out photosynthesis. The leaves of most plants are green because they contain chlorophyll. Chlorophyll can only use light energy to synthesize various organic substances. This process is called photosynthesis. According to calculation, green plants all over the world can produce about 400 million tons of protein, carbohydrates and fat every day, and at the same time release nearly 500 million tons of oxygen into the air, providing sufficient food and oxygen for people and animals.
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