Tilting results in longer days in the northern hemisphere from the spring (vernal) equinox to the fall (autumnal) equinox and longer days in the southern hemisphere during the other 6 months. The 23.5° tilt in the Earth's axis of rotation is a more significant factor in determining the amount of sunlight striking the Earth at a particular location. However, the presence of vast oceans moderates the hotter summers and colder winters one would expect to see in the southern hemisphere as a result of this difference. The Earth is nearer the sun when it is summer in the southern hemisphere and winter in the northern hemisphere. When the sun is nearer the Earth, the Earth's surface receives a little more solar energy. The Earth revolves around the sun in an elliptical orbit and is closer to the sun during part of the year. Because the Earth is round, the frigid polar regions never get a high sun, and because of the tilted axis of rotation, these areas receive no sun at all during part of the year. The more slanted the sun's rays are, the longer they travel through the atmosphere, becoming more scattered and diffuse. When the sun's rays are vertical, the Earth's surface gets all the energy possible. The amount of solar radiation that reaches any one spot on the Earth's surface varies according to:īecause the Earth is round, the sun strikes the surface at different angles, ranging from 0° (just above the horizon) to 90° (directly overhead). Basic PrinciplesĮvery location on Earth receives sunlight at least part of the year. However, the technical feasibility and economical operation of these technologies at a specific location depends on the available solar resource. Solar radiation can be captured and turned into useful forms of energy, such as heat and electricity, using a variety of technologies. Lightning is an example of electrical energy in nature.Solar radiation, often called the solar resource or just sunlight, is a general term for the electromagnetic radiation emitted by the sun. Typically, the energy in sound is smaller than in other forms of energy.Įlectrical energy is delivered by tiny, charged particles called electrons, that typically move through a wire. The energy is transferred through the substance in a wave. Sound is produced when a force causes an object or substance to vibrate. Sound is energy moving through substances in longitudinal (compression/rarefaction) waves. A dramatic example of motion energy is a car crash-a car comes to a total stop and releases all of its motion energy at once in an uncontrolled instant. It takes energy to get an object moving, and energy is released when an object slows down. The faster an object moves, the more energy is stored. Motion energy is energy stored in moving objects. Geothermal energy is the thermal energy in the earth. Heat increases when these particles move faster. Thermal energy, or heat, is the energy that comes from the movement of atoms and molecules in a substance. Sunshine is radiant energy, which provides the fuel and warmth that make life on earth possible. Radiant energy includes visible light, x-rays, gamma rays, and radio waves. Radiant energy is electromagnetic energy that travels in transverse waves. Kinetic energy is the motion of waves, electrons, atoms, molecules, substances, and objects. Hydropower is another example of gravitational energy, where gravity forces water down through a hydroelectric turbine to produce electricity. When a person rides a bicycle down a steep hill and picks up speed, the gravitational energy is converting to motion energy. The higher and heavier the object, the more gravitational energy is stored. Gravitational energy is energy stored in an object's height. Large amounts of energy can be released when the nuclei are combined or split apart. Nuclear energy is energy stored in the nucleus of an atom-the energy that holds the nucleus together. Compressed springs and stretched rubber bands are examples of stored mechanical energy. Mechanical energy is energy stored in objects by tension. For example, chemical energy is converted to thermal energy when people burn wood in a fireplace or burn gasoline in a car's engine. Batteries, biomass, petroleum, natural gas, and coal are examples of chemical energy. Potential energy is stored energy and the energy of position.Ĭhemical energy is energy stored in the bonds of atoms and molecules.
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