Radiation from the sun All of the Sun's energy that reaches the Earth arrives as solar radiation, which is part of a huge collection of energy known as the electromagnetic radiation spectrum. Visible light, ultraviolet light, infrared light, radio waves, X-rays, and gamma rays are all types of solar radiation. Radiation is one method of transferring heat. Heat is the basis of all life on Earth, and without it there would be no people, just plants and animals frozen in ice.
Of all the types of solar radiation our planet receives, only a small amount reaches the surface. The rest is either absorbed by clouds or landmasses or reflected back into space. Solar radiation is classified according to its wavelength: longwave radiation has wavelengths longer than about 10 microns, while shortwave radiation has wavelengths shorter than about 10 microns. Different materials reflect light of different wavelengths differently; for example, glass reflects about 90 percent of the light that falls on it, while aluminum reflects almost all light that strikes it.
The portion of solar radiation that reaches the surface consists of longwave radiation and shortwave radiation. Shortwave radiation accounts for only 4% of the total solar radiation that reaches the Earth's atmosphere, but it plays an important role in our environment because it is what causes sunlight to heat up objects such as water molecules and minerals in the soil. The longwave radiation that reaches the ground is much more abundant - 93% - but it is low-energy radiation that is not very effective at heating things up.
The majority of the electromagnetic energy emitted by the sun is invisible to us. Only a small percentage of it is visible light. The atmosphere absorbs the majority of solar radiation, and much of what reaches the earth's surface is reflected back into the atmosphere to create heat energy. Some of this radiation makes its way to the surface and is absorbed by landmasses and stored as thermal energy in the rocks and soil. This is why places like Hawaii and Alaska are hot despite the fact that they are so far away from the equator! The radiation also causes clouds to form and evaporate, which can have an impact on rainfall here on Earth.
Only a small fraction of the solar energy reaching the earth is radiated toward space. Most is either absorbed by other substances or is conducted through conductors such as water or metal. If enough energy is available, it can even be used to split molecules, producing free radicals that can cause damage to living things or change the properties of materials such as wood or plastic.
Radiation is the term used to describe anything that travels in waves, including light and radio waves. Solar radiation is energy released by the sun during electron transitions between higher energy levels of the atoms making up the sun. It consists of electromagnetic waves and particles called photons.
The Solar System The sun provides the majority of the energy that reaches the Earth's surface. Although visible light wavelengths account for around 44 percent of solar energy, the Sun also emits infrared, ultraviolet, and other wavelengths. Visible light is just about all we can see with our eyes; everything else is invisible. The Earth uses this energy to heat itself up and maintain a moderate temperature.
The Earth orbits the Sun at a distance of 150 million km (93 million miles). This means that on average, the Earth gets hit by $150\,000$ megatons of solar radiation each day. That's five times the total nuclear weapon explosion in history! Most of this energy is received over oceans, but some of it is also reflected back out into space. Oceans reflect around 30 percent of the incoming sunlight, so half of it reaches the Earth's surface.
Solar flares are bursts of radiation from the Sun that can affect satellites and earth-based technology. They are caused by magnetic fields inside the Sun breaking down causing an eruption of particles that flow away from the Sun at around 10 million kms per hour. If these particles reach Earth they can cause power surges on wires connecting to our electrical systems, but there are also concerns that they could impact electronics on board spacecraft or even trigger a nuclear reactor under certain conditions.
Infrared, which has lower frequencies than red light, and ultraviolet, which has higher frequencies than violet light, are solar waves that we cannot perceive. The bulk of solar radiation is absorbed by the atmosphere, and much of what reaches the earth's surface is reflected back into the atmosphere to create heat energy. Some of this infrared radiation makes it through the atmosphere and into space where it contributes to global warming.
Solar radiation is classified as visible light, ultraviolet (UV) light, and infrared (IR) light. Visible light is made up of photons with wavelengths from about 400 nm (blue) to 700 nm (red). Ultraviolet light has wavelengths shorter than visible light but longer than X-rays (about 10-15 nm). Infrared light has wavelengths between 0.7 mm (violet) and 5 mm (white). Most solar radiation is composed of invisible light called blackbody radiation. Blackbody radiation is emitted by objects that are hot enough to emit all wavelengths of light equally. For example, your body emits blackbody radiation at around 310 K (90 F), while the sun's surface is about 5800 K (1150 F).
Photons with energies greater than the binding energy of an atom will be able to escape the atom's gravitational pull. These photons form the basis for understanding how light is transmitted through a vacuum without interacting with anything else. In fact, light can travel through almost any material if it is in sufficient quantities.
Solar radiation is the primary source of energy in our climate system, and practically all climatic and biological activities on Earth rely on it. The sun's energy is required for numerous activities on Earth, including surface warming, evaporation, photosynthesis, and atmospheric circulation. In addition to these physical processes, solar radiation is responsible for the formation of clouds, which have a profound effect on Earth's atmosphere and climate.
In general, solar radiation is electromagnetic radiation that is emitted by the Sun into space. However, due to absorption of some parts of this radiation by molecules in the atmosphere, most of it is converted into thermal energy that warms the atmosphere and surfaces around us. This process, which is called scattering or extinction, depends on the wavelength of the light being scattered or extinguished. For visible light (which makes up over 95% of sunlight) extinction by oxygen in the air is the main cause of cooling during daylight hours when there are no clouds present. During twilight and at night time, however, when clouds are present, most of the visible light is reflected back out to space instead of being absorbed by molecules in the atmosphere.
The portion of the solar spectrum that is responsible for heating Earth's surface is known as the infrared spectrum.