The sun plays an important role for us on Earth. It provides the planet and everything on it with important factors such as light and heat. But what is solar radiation, the spectrum of sunlight, how does all this affect us and the global climate as a whole?
What is solar radiation?
Bad thoughts usually come to mind when you think of the word "radiation." But solar radiation is actually a very good thing - it's sunlight! Every living creature on Earth depends on him. It is necessary for survival, warms the planet, provides nutrition for plants.
Solar radiation is all the light and energy that comes from the sun, and there are many different forms of it. The electromagnetic spectrum distinguishes between various types of light waves emitted by the sun. They look like the waves you see in the ocean: they move up and down and from one place to another. The spectrum of solar studies can have different intensities. Distinguish between ultraviolet, visible and infrared radiation.
Light is moving energy
The spectrum of solar radiation is figuratively reminiscent of a piano keyboard. One end has low notes, while the other has high notes. The same applies to the electromagnetic spectrum. One end has low frequencies and the other high. Low-frequency waves are long for a given period of time. These are things like radar, TV and radio waves. High-frequency emissions are short-wave high-energy waves. This means that the wavelength itself is very short for a given period of time. These are, for example, gamma rays, x-rays and ultraviolet rays.
You can think of it this way: low-frequency waves are like climbing a hill with a gradual ascent, while high-frequency waves are like climbing up a steep, almost vertical hill. The height of each hill is the same. The frequency of an electromagnetic wave determines how much energy it carries. Electromagnetic waves, which have a longer length and therefore lower frequencies, carry much less energy than with shorter lengths and higher frequencies.
This is why x-rays and ultraviolet radiation can be dangerous. They carry so much energy that if they enter your body, they can damage cells and cause problems like cancer and a change in DNA. Things like radio and infrared waves that carry far less energy do not really have any effect on us. This is good, because you certainly do not want to put yourself at risk by simply turning on the stereo.
The visible light that we and other animals can see with our eyes is located almost in the middle of the spectrum. We do not see any other waves, but this does not mean that they are not there. In fact, insects see ultraviolet light, but not our visible. Flowers look completely different for them than they do for us, and this helps them to know which plants to visit and which ones to stay away from.
Source of all energy
We take sunlight for granted, but it doesn’t have to be so, because, in fact, all the energy on Earth depends on this large, bright star in the center of our solar system. And while we are in it, we must also say thanks to our atmosphere, because it absorbs part of the radiation before it reaches us. This is an important balance: too much sunlight, and it gets hot on Earth, too little - and it starts to freeze.
Passing through the atmosphere, the spectrum of solar radiation at the surface of the Earth gives energy in various forms. To begin, consider the various ways to transmit it:
- Conductivity (conduction) is when energy is transferred from direct contact. When you burn your hand with a hot pan, because you forgot to put on a tack, this is conductivity. The cookware transfers heat to your hand through direct contact. In addition, when your feet touch the cold tile in the bathroom in the morning, they transfer heat to the floor through direct contact - conductivity in action.
- Dissipation is when energy is transmitted through currents in a fluid. It can also be gas, but the process will be the same anyway. When the liquid is heated, the molecules are excited, scattered and less dense, so they tend upward. When they cool, they again fall down, creating a cellular current path.
- Radiation (radiation) is when energy is transmitted in the form of electromagnetic waves. Think about how good it is to sit next to a bonfire and feel how welcome heat radiates from it to you - this is radiation. Radio waves, light and heat waves can travel, moving from one place to another without the help of any materials.
The main spectra of solar radiation
The sun has different radiation: from x-rays to radio waves. Solar energy is light and heat. Its composition:
- 6-7% ultraviolet light,
- about 42% of the visible light,
- 51% near infrared.
We get solar energy at an intensity of 1 kilowatt per square meter at sea level for many hours a day. About half of the radiation is in the visible short-wave part of the electromagnetic spectrum. The other half is in the near infrared, and a little in the ultraviolet.
Ultraviolet radiation
It is ultraviolet radiation in the solar spectrum that has an intensity greater than others: up to 300-400 nm. Part of this radiation, which is not absorbed by the atmosphere, produces a tan or sunburn for people who have been in sunlight for extended periods of time. Ultraviolet radiation in sunlight has both positive and negative effects on health. It is the main source of vitamin D.
Visible radiation
The visible radiation in the solar spectrum has an average level intensity. Quantitative estimates of the flux and variations in its spectral distribution in the visible and near infrared ranges of the electromagnetic spectrum are of great interest in the study of solar-terrestrial effects. The range from 380 to 780 nm is visible to the naked eye.
The reason is that the bulk of the energy of solar radiation is concentrated in this range and it determines the thermal equilibrium of the Earth’s atmosphere. Sunlight is a key factor in the process of photosynthesis, used by plants and other autotrophic organisms to convert light energy into chemical energy, which can be used as fuel for the body.
Infrared radiation
The infrared spectrum, which covers from 700 nm to 1,000,000 nm (1 mm), contains an important part of the electromagnetic radiation that reaches the Earth. Infrared radiation in the solar spectrum has an intensity of three types. Scientists divide this range into 3 types based on wavelength:
- A: 700-1400 nm.
- B: 1400-3000 nm.
- C: 3000-1 mm.
Conclusion
Many animals (including humans) have a sensitivity in the range of about 400-700 nm, and a useful spectrum of color vision in humans, for example, is about 450-650 nm. In addition to the effects that occur at sunset and sunrise, the spectral composition changes, first of all, in relation to how direct sunlight enters the earth.
Every two weeks, the Sun supplies our planet with so much energy that it is enough for all the inhabitants for a whole year. In this regard, solar radiation is increasingly being considered as an alternative source of energy.