Energy

Energy All life on Earth depends on energy from the sun. Solar energy is the source of energy for photosynthesis. It provides the warmth necessary for plants and animals to survive. The heat from the sun causes water on the Earth's surface to evaporate and form clouds that eventually provide fresh rainwater. Solar energy is the result of thermonuclear fusion reactions deep within the sun. These reactions produce so much energy that they keep the surface temperature of the sun at about 10,300B0F. Even though solar energy is the largest source of energy received by the Earth, its intensity at the Earth's surface is actually very low due to the large distance between the Earth and the sun and the fact that the Earth's atmosphere absorbs and scatters some of the radiation. Even on a clear day with the sun directly overhead, the energy that reaches the Earth's surface is reduced about 30 percent by the atmosphere. When the sun is near the horizon and the sky is overcast, the solar energy at ground level can be negligible. It also varies from one point to another on the Earth's surface. Nevertheless, in the 20th century, the sun's energy has become an energy, collectors, solar, sun, surface, heat, temperatures, one, flat-plate, earth's, power, earth, concentrating, about, target, sun's, source, radiation, produce, mirror, concentrate, collector, another, water, varies, transferred, tower, times, sunlight, steam, single, received, reactions, provide, plate, plant, percent, near, must, low, large, intensity, higher, generates, furnace, fluids, example, even, electricity, efficiency, directly