Everything you need to know about solar radiation on the Earth's surface

The Earth receives various forms of radiation, but the main source is radiation emitted by the SunThis phenomenon is possible thanks to the nuclear fusion that occurs in the solar core, where hydrogen transforms into helium, releasing enormous amounts of thermal energy. This energy travels from the heart of the Sun to its surface and is finally emitted into space, reaching our planet. To learn more about the characteristics of this phenomenon, you can consult the solar radiation.

Solar energy reaches the Earth in the form of electromagnetic waves, which have different wavelengths. The set of all these wavelengths emitted by a body is called spectrumThis spectrum is intrinsically linked to the temperature of the emitting object, so that at higher temperatures, the emitted wavelengths are shorter.

The solar spectrum is composed mainly of short wavelengths, a result of the extremely high temperature of the Sun, which is estimated to be around 6.000 K (equivalent to 5.727 ºC).

Types of solar radiation

Within the solar spectrum, three fundamental types of radiation can be identified:

1. Ultraviolet rays: With wavelengths ranging from 0,1 to 0,4 micrometers, UV rays account for about 9% of the total energy emitted by the Sun. This form of radiation is especially important because it can cause harmful health effects, such as sunburn and an increased risk of skin cancer. For more details on the effects of this radiation, you can visit the section on types of solar radiation.
2. Visible rays: This radiation has wavelengths ranging from 0,4 to 0,78 micrometers, constituting approximately 41% of total solar energy. This is the range of radiation we can perceive with our eyes and is essential for photosynthesis in plants, which in turn supports most food chains on Earth.
3. Infrared rays: With wavelengths ranging from 0,78 to 3 micrometers, infrared rays comprise the remaining 50% of the sun's energy. This radiation is crucial for warming the Earth's surface and affects our planet's climate and environmental conditions. You can learn more about how this radiation impacts the climate at solar activity and climate change.

Once these solar radiations reach the surface, they are distributed unevenly across different latitudes, due to how the Earth-atmosphere system intercepts solar energy. This phenomenon results in significant variations in the amount of radiation received in different regions of the world.

The solar constant and its variability

The amount of solar radiation reaching the Earth's surface varies due to the distance between our planet and the Sun. This average value is known as the solar constant, which ranges between 1.325 and 1.412 W/m², depending on the Earth's relative position in its orbit. On average, this constant is considered to be approximately E = 1366 W/m². For more information on how this constant is measured and behaves, you can consult solar radiation on planet Earth.

Components of solar radiation and their interaction with the atmosphere

Solar radiation entering the Earth's atmosphere does not reach the surface intact; it undergoes various interaction phenomena:

• Direct radiation: This component comes directly from the Sun and is responsible for the shadows cast by objects. It is stronger on sunny days and weaker when there are clouds.
• Diffuse radiation: It results from the scattering of solar radiation by particles in the atmosphere. This component can represent up to 15% of total radiation on sunny days and increases as the sky becomes cloudier.
• Albedo or reflected radiation: Radiation reflected by the Earth's surface. Its amount depends on the surface's reflection coefficient. For example, the albedo of snow can reach up to 80%, meaning that snow reflects a large proportion of solar radiation.

This management and distribution of solar radiation are essential to understanding various climatic and meteorological phenomena that affect life on our planet. To better understand the impacts of solar events on Earth, you can review details about solar storms, which can affect conditions on the Earth's surface.

Solar radiation reaching the Earth's surface is a complex phenomenon involving various forms of energy, their interactions with the atmosphere, and their variability depending on factors such as latitude and altitude. Understanding this phenomenon is not only crucial for meteorology and climatology, but also for sustainably harnessing this inexhaustible source of energy in technologies such as solar photovoltaics, which promise to be key in the transition toward a more sustainable energy future.

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