What is solar radiation? Definition, classification, and measurement methods

Solar radiation is an abundant and inexhaustible source of energy, playing a crucial role in sustaining life on Earth. So, what is solar radiation? How is it classified? And how is its intensity measured? Let’s explore these details with Reecotech in this article!

What is Solar Radiation?

Solar radiation is the combination of material and energy flows emitted by the Sun. It not only provides energy for weathering, erosion, and deposition processes on Earth’s surface but also plays a role in illuminating and warming other planets in the Solar System.

Solar radiation emits a vast amount of energy, with approximately 30% reflected back into space, 19% absorbed by the atmosphere, and 47% absorbed by Earth, while the remaining 4% is reflected back into space. However, the distribution of solar radiation on Earth’s surface is uneven, leading to significant differences in illumination and temperature across different regions.

The Role of Solar Radiation for Earth

Solar radiation plays a crucial role for Earth and all life on this planet. Specifically, it has the following impacts:

• Providing Energy for Biological Processes: Solar radiation is the primary energy source for photosynthesis in plants, which produces food for both plants and animals. Additionally, solar radiation provides energy for other photochemical processes, such as oxygen production in the atmosphere.
• Forming Weather and Climate Phenomena: Solar radiation is the main energy driver behind natural phenomena like wind, rain, and storms. These phenomena have a profound impact on human life and ecosystems on Earth.
• Warming the Earth: Solar radiation helps maintain Earth’s average temperature, keeping the planet warm enough to support life. Without solar radiation, Earth would become a cold, lifeless planet.

Classification of Solar Radiation

When studying solar radiation, it’s important to understand how to classify the common types of radiation. Solar radiation can be classified in two main ways: by nature and by wavelength.

Classification by Nature of Radiation

Electromagnetic Radiation: This type accounts for about 99% of the total energy emitted by the Sun. It includes various types of waves, ranging from gamma rays to radio waves.

Particle Radiation: Comprising about 1% of the total solar radiation energy, particle radiation consists of charged particles such as protons, electrons, and atomic nuclei.

Classification by Wavelength of Radiation

• Ultraviolet (UV) Radiation: With wavelengths ranging from 0.01 to 0.38 microns, UV radiation can be harmful to human skin and eyes.
• Visible Radiation: With wavelengths from 0.38 to 0.76 microns, this is the range of light visible to the human eye.
• Infrared Radiation: Spanning wavelengths from 0.76 to 1000 microns, this type of radiation can contribute to the greenhouse effect, warming the Earth.
• Radio Waves: With wavelengths greater than 1000 microns, radio waves are commonly used in communications and broadcasting.

Additionally, solar radiation can also be classified by intensity, distribution direction, and distribution time.

=> Learn more: Solar radiation measurement devices at Reecotech

What is Solar Radiation Intensity?

Solar radiation intensity is a physical quantity used to measure the amount of energy that sunlight brings to a specific area per unit of time, usually expressed in watts per square meter (W/m²). This indicates the amount of solar energy reaching a particular area.

Solar radiation intensity is calculated using the formula:

H = I x t

Where:

• H is the solar radiation intensity (W/m²).
• I is the average solar radiation intensity (W/m²).
• t is the measurement time (hours).

Solar radiation intensity can be measured using photonic devices, which operate based on the principle of converting solar radiation energy into electrical energy. Common types of measuring devices include:

• Solarimeters: These are the most common devices, using a round sensor covered with a light-sensitive material to measure the current generated when light strikes it.
• Photodetectors: These electronic devices can convert light into electrical energy, measuring solar radiation intensity through the voltage or current generated.

In Vietnam, the average solar radiation intensity ranges from about 5 kW/h/m²/day in the central and southern provinces to around 4 kW/h/m²/day in the northern provinces. This level varies with seasons and terrain, being highest in the summer and lowest in the winter, with higher intensities in mountainous regions and lower in the plains.

The Impact of Solar Radiation

In this section, we will examine the positive and negative effects of solar radiation on life on Earth.

Positive Impacts of Solar Radiation

Solar radiation is a natural, abundant, and inexhaustible source of energy that provides many benefits for life on Earth, including:

• Renewable Energy Source: Solar radiation can be harnessed to generate electricity, heat, and fuel. It is a clean, sustainable energy source that helps reduce environmental pollution and contributes to mitigating climate change.
• Applications in Agriculture: Sunlight is essential for the photosynthesis process in plants, helping them produce energy for growth and development, thereby increasing agricultural productivity.
• Medical Uses: Solar radiation can be applied in the treatment of certain conditions such as psoriasis, eczema, and vitiligo through light therapies.
• Positive Effects on Mental Health: Exposure to sunlight can improve mood, reduce stress and fatigue, and contribute to better mental health.

Negative Impacts of Solar Radiation

While solar radiation provides many benefits, it can also have several negative effects on life on Earth, including:

• Sunburn: Solar radiation can cause sunburn, leading to redness, pain, and swelling of the skin. If not treated promptly, this condition can potentially lead to skin cancer.
• Skin Cancer: Solar radiation is a major cause of skin cancer, including squamous cell carcinoma, basal cell carcinoma, and melanoma. These are serious diseases that can be fatal if not treated.
• Cataracts: Prolonged exposure to solar radiation can increase the risk of developing cataracts, a condition that clouds the lens of the eye.
• Macular Degeneration: Solar radiation can also raise the risk of macular degeneration, an eye disease that leads to a loss of vision.
• Immune System Suppression: Solar radiation can weaken the immune system, making the body more susceptible to infections.
• Heart Rhythm Disorders: Solar radiation can cause heart rhythm disturbances, leading to irregular heartbeats.

Solar radiation is a natural phenomenon that provides a plentiful source of energy for life on Earth. Understanding its effects is crucial for effectively and sustainably harnessing and using this energy source. In this article, we have explored the definition of solar radiation, its classification methods, and how to measure its intensity.