La solar radiation It is a very important variable used to determine the amount of heat we receive from the sun at the Earth's surface. Depending on factors such as wind, cloud cover, and the season, we receive a greater or lesser amount of solar radiation. It has the ability to heat the surface of the ground and objects without barely heating the air. There are different types of solar radiation depending on their source and characteristics.
Learn all about solar radiation, the types that exist, and their effects on the planet and life.
What is solar radiation
It is the flow of energy that is received by the sun in the form of electromagnetic waves of different frequencies. Among the frequencies that we find in the electromagnetic spectrum we have the best known as visible, infrared and ultraviolet light. We know that almost half of the solar radiation that our planet receives has a frequency comprised between the ranges of 0.4μm and 0.7μm. This type of radiation can be detected by the human eye and is what constitutes the strip that we know as visible light.
The other half is mostly in the infrared part of the spectrum and a small part in the ultraviolet. To be able to measure how much radiation we receive from the sun an instrument known as a pyranometer is used. In addition, through studies related to the radiation at the Earth's surface, we can better understand the effects of this energy and how they relate to the Types of solar radiation, characteristics and operation.
Types of solar radiation
Depending on the origin and characteristics of solar radiation, there are different types. We are going to focus on defining what the different types are and their main characteristics:
Direct solar radiation
It is about the one that it comes directly from the sun and undergoes little change in directions. This radiation can be influenced by wind, but not greatly. A reduction in heat can be perceived during windy days. On surfaces, the heat does not affect them as strongly when there is a strong wind. This type of radiation has a main characteristic: it can cast a defined shadow on any opaque object that intercepts it. It is essential in many studies on solar radiation and its impact on the environment, and it is also important to understand its influence on the solar minimum.
Diffuse solar radiation
It is a part of the radiation that reaches us from the sun and that is reflected by or absorbed by clouds. It is known by the name of diffuse since they extend in all directions. This process takes place due to reflections and absorptions, not only from clouds, but from some particles that exist floating in the atmosphere. These particles are called atmospheric dust and are capable of diffusing solar radiation. It is also called diffuse since it is deflected by some objects such as mountains, trees, buildings and the ground itself, depending on its constitution.
The main characteristic of this radiation is that it does not cast a shadow on opaque objects that are interposed. Horizontal surfaces are those places where there is the greatest amount of diffuse radiation. The opposite occurs with vertical surfaces, since there is hardly any contact. It is interesting to observe how these aspects relate to events such as the solar eclipse.
Reflected solar radiation
It is one that reflects the earth's surface. Not all the radiation that reaches us from the sun is absorbed by the surface, but some of it is deflected. This amount of radiation that is deflected from the surface is known as albedo. The Earth's albedo is increasing largely due to the effects of climate change and the melting of the polar ice caps. To better understand this phenomenon, it is recommended to consult information on how it influences and relates to the cosmic radiation.
The surfaces that are horizontal do not receive any type of reflected radiation since they do not see any terrestrial surface. The opposite is the case with diffuse solar radiation. In this case, it is the vertical surfaces that receive the greatest amount of reflected radiation.
Global solar radiation
It can be said that it is the total radiation that exists on the planet. It is the sum of the 3 radiations mentioned above. Let's take the example of a completely sunny day. Here we will have direct radiation, which will be greater than diffuse radiation. However, on a cloudier day there will be no direct radiation, but rather all the incident radiation will be diffuse. This information is key when studying phenomena such as solar eclipse and how it can affect solar radiation.
How it affects life and the planet
If the amount of solar radiation that our planet receives, life could not arise as it has. The energy balance of the Earth is 0. This means that the amount of solar radiation that the planet receives and that which it emits back to outer space is the same. However, some nuances must be added. In that case the temperature on the planet would be -88 degrees. So you need something that can retain this radiation and make the temperature levels comfortable and habitable so that it can support life.
The greenhouse effect is the driving force that helps ensure that a large portion of the solar radiation that falls on the Earth's surface is retained. Thanks to the greenhouse effect, we maintain habitable conditions on the planet. When solar radiation hits the surface, almost half of it is returned to the atmosphere, expelled into outer space. Part of this radiation returning from the surface is absorbed and reflected by clouds and atmospheric dust. However, this amount of absorbed radiation is not enough to maintain a stable temperature.
This is where greenhouse gases come in. It is a variety of gases that have the ability to retain part of the heat emitted by the earth's surface, returning the solar radiation that has reached it back to the atmosphere. Greenhouse gases are as follows: water vapor, carbon dioxide (CO2), nitrogen oxides, sulfur oxides, methane, etc. With the increase in greenhouse gases due to human activities, solar radiation is becoming more harmful, as it impacts the environment, flora, fauna, and humans. To delve deeper into this, it is interesting to research solar activity and its effect on climate change.
The sum of all types of solar radiation are those that allow life on the planet. Let's hope that the problems of the increase in greenhouse gases can be alleviated and the situation does not become dangerous.