Solar radiation - what is it? Total solar radiation. Solar radiation: types

SOLAR RADIATION- electromagnetic and corpuscular radiation from the Sun. Electromagnetic radiation travels as electromagnetic waves at the speed of light and penetrates the earth's atmosphere. To earth's surface Solar radiation comes in the form of direct and diffuse radiation.
Solar radiation - main source energy for all physical and geographical processes occurring on the earth's surface and in the atmosphere (see Insolation). Solar radiation is usually measured by its thermal effect and is expressed in calories per unit surface area per unit time. In total, the Earth receives less than one two billionth of its radiation from the Sun.
The spectral range of electromagnetic radiation from the Sun is very wide - from radio waves to X-rays - but its maximum intensity falls on the visible (yellow-green) part of the spectrum.
There is also a corpuscular part of solar radiation, consisting mainly of protons moving from the Sun at speeds of 300-1500 km/s (solar wind). During solar flares, high-energy particles (mainly protons and electrons) are also produced, forming the solar component of cosmic rays.
The energy contribution of the corpuscular component of solar radiation to its overall intensity is small compared to the electromagnetic one. Therefore, in a number of applications the term “solar radiation” is used in a narrow sense, meaning only its electromagnetic part.
The amount of solar radiation depends on the height of the sun, time of year, and transparency of the atmosphere. Actinometers and pyrheliometers are used to measure solar radiation. The intensity of solar radiation is usually measured by its thermal effect and is expressed in calories per unit surface area per unit time.
Solar radiation strongly affects the Earth only during the daytime, of course - when the Sun is above the horizon. Also, solar radiation is very strong near the poles, during polar days, when the Sun is above the horizon even at midnight. However, in winter, in the same places, the Sun does not rise above the horizon at all, and therefore does not affect the region. Solar radiation is not blocked by clouds, and therefore still reaches the Earth (when the Sun is directly above the horizon). Solar radiation is a combination of the bright yellow color of the Sun and heat, heat also passes through clouds. Solar radiation is transmitted to Earth by radiation, not by thermal conduction.
The amount of radiation received by a celestial body depends on the distance between the planet and the star - as the distance doubles, the amount of radiation received from the star to the planet decreases fourfold (proportional to the square of the distance between the planet and the star). Thus, even minor changes the distances between the planet and the star (depending on the eccentricity of the orbit) lead to a significant change in the amount of radiation entering the planet. The eccentricity of the earth's orbit is also not constant - over the course of millennia it changes, periodically forming an almost perfect circle, sometimes the eccentricity reaches 5% (currently it is 1.67%), that is, at perihelion the Earth currently receives 1.033 more solar radiation than at aphelion, and at the greatest eccentricity - more than 1.1 times. However, the amount of incoming solar radiation depends much more strongly on the changes of the seasons - currently the total amount of solar radiation entering the Earth remains practically unchanged, but at latitudes of 65 N.Sh (the latitude of the northern cities of Russia and Canada) in the summer the amount of incoming solar radiation more than 25% more than in winter. This occurs because the Earth is tilted at an angle of 23.3 degrees in relation to the Sun. Winter and summer changes are mutually compensated, but nevertheless, as the latitude of the observation site increases, the gap between winter and summer becomes larger and larger, so at the equator there is no difference between winter and summer. Beyond the Arctic Circle, solar radiation is very high in summer and very low in winter. This shapes the climate on Earth. In addition, periodic changes in the eccentricity of the Earth's orbit can lead to the emergence of different geological eras: for example,

General hygiene. Solar radiation and its hygienic significance.

By solar radiation we mean the entire flux of radiation emitted by the Sun, which is electromagnetic oscillations of various wavelengths. From a hygienic point of view, the optical part of sunlight, which occupies the range from 280-2800 nm, is of particular interest. Longer waves are radio waves, shorter ones are gamma rays, ionizing radiation do not reach the Earth's surface because they are retained in the upper layers of the atmosphere, in the ozone layer in particular. Ozone is distributed throughout the atmosphere, but at an altitude of about 35 km it forms the ozone layer.

The intensity of solar radiation depends primarily on the height of the sun above the horizon. If the sun is at its zenith, then the path taken by the sun's rays will be much shorter than their path if the sun is at the horizon. By increasing the path, the intensity of solar radiation changes. The intensity of solar radiation also depends on the angle at which the sun's rays fall, and the illuminated area also depends on this (as the angle of incidence increases, the area of ​​illumination increases). Thus, the same solar radiation falls on a larger surface, so the intensity decreases. The intensity of solar radiation depends on the mass of air through which the sun's rays pass. The intensity of solar radiation in the mountains will be higher than above sea level, because the layer of air through which the sun's rays pass will be less than above sea level. Special significance represents the influence of the state of the atmosphere and its pollution on the intensity of solar radiation. If the atmosphere is polluted, then the intensity of solar radiation decreases (in the city, the intensity of solar radiation is on average 12% less than in rural areas). The voltage of solar radiation has a daily and annual background, that is, the voltage of solar radiation changes throughout the day, and also depends on the time of year. The highest intensity of solar radiation is observed in summer, the lowest in winter. In terms of its biological effect, solar radiation is heterogeneous: it turns out that each wavelength has an different action on the human body. In this regard, the solar spectrum is conventionally divided into 3 sections:

1. ultraviolet rays, from 280 to 400 nm

2. visible spectrum from 400 to 760 nm

3. infrared rays from 760 to 2800 nm.

With daily and annual solar radiation, the composition and intensity of individual spectra undergo changes. The rays of the UV spectrum undergo the greatest changes.

We estimate the intensity of solar radiation based on the so-called solar constant. The solar constant is the amount of solar energy received per unit time per unit area located at the upper boundary of the atmosphere at right angles to the sun's rays at the average distance of the Earth from the Sun. This solar constant was measured by satellite and is equal to 1.94 calories/cm 2

Voltage sun rays at noon in May in Yalta 1.33, in Moscow 1.28, in Irkutsk 1.30, in Tashkent 1.34.

Biological significance of the visible part of the spectrum.

The visible part of the spectrum is a specific irritant of the organ of vision. Light is a necessary condition for the functioning of the eye, the most subtle and sensitive sense organ. Light provides approximately 80% of information about the outside world. This is the specific effect of visible light, but also the general biological effect of visible light: it stimulates the body’s vital activity, enhances metabolism, improves overall well-being, affects the psycho-emotional sphere, and increases performance. Light makes you healthier environment. With a lack of natural light, changes occur in the organ of vision. Fatigue sets in quickly, performance decreases, and work-related injuries increase. The body is affected not only by illumination, but also different colors have different effects on the psycho-emotional state. The best performance indicators were obtained with the preparation under yellow and white lighting. Psychophysiologically, colors act opposite to each other. In this regard, 2 groups of colors were formed:
1) warm colors - yellow, orange, red. 2) cold tones - blue, blue, violet. Cold and warm tones have different physiological effects on the body. Warm tones increase muscle tension, increase blood pressure, and increase the breathing rate. Cold tones, on the contrary, lower blood pressure and slow down the rhythm of the heart and breathing. This is often used in practice: for patients with high temperature Wards painted purple are most suitable; dark ocher improves the well-being of patients with low blood pressure. Red color increases appetite. Moreover, the effectiveness of the drug can be increased by changing the color of the tablet. Patients suffering from depressive disorders were given the same medicine in tablets of different colors: red, yellow, green. Treatment with yellow tablets brought the best results.

Color is used as a carrier of coded information, for example in production to indicate danger. There is a generally accepted standard for signal identification colors: green - water, red - steam, yellow - gas, orange - acids, purple - alkalis, brown - flammable liquids and oils, blue - air, gray - other.

From a hygienic point of view, the assessment of the visible part of the spectrum is carried out according to the following indicators: natural and artificial lighting are assessed separately. Natural lighting is assessed according to 2 groups of indicators: physical and lighting. The first group includes:

1. light coefficient -- characterizes the ratio of the area of ​​the glazed surface of the windows to the floor area.

2. Angle of incidence - characterizes the angle at which the rays fall. According to the norm, the minimum angle of incidence should be at least 270.

3. The angle of the hole - characterizes the illumination by heavenly light (must be at least 50). On the first floors of Leningrad houses - wells, this angle is virtually absent.

4. The depth of the room is the ratio of the distance from the top edge of the window to the floor to the depth of the room (the distance from the outer to the inner wall).

Lighting indicators are indicators determined using a device - a lux meter. Absolute and relative illumination is measured. Absolute illumination is the illumination on the street. Illuminance coefficient (KEO) is defined as the ratio of relative illuminance (measured as the ratio of relative illuminance (measured in a room) to absolute, expressed in %. Illumination in a room is measured at the workplace. The principle of operation of a lux meter is that the device has a sensitive photocell (selenium - since selenium is close in sensitivity to the human eye). The approximate illumination on the street can be determined using a light climate graph.

To evaluate artificial lighting of premises, brightness, lack of pulsation, color, etc. are important.

Infrared rays. The main biological effect of these rays is thermal, and this effect also depends on the wavelength. Short rays carry more energy, so they penetrate deeper and have a strong thermal effect. The long section exerts its thermal effect on the surface. This is used in physiotherapy to warm up areas at different depths.

In order to measure infrared rays, there is a device - an actinometer. Infrared radiation is measured in calories per cm2\min. The adverse effects of infrared rays are observed in hot shops, where they can lead to occupational diseases - cataracts (clouding of the lens). Cataracts are caused by short infrared rays. A preventative measure is the use of protective glasses and protective clothing.

Features of the impact of infrared rays on the skin: burns occur - erythema. It occurs due to thermal expansion of blood vessels. Its peculiarity is that it has different boundaries and appears immediately.

Due to the action of infrared rays, 2 conditions of the body can occur: heatstroke and sunstroke. Sunstroke is the result of direct exposure to sunlight on the human body, mainly with damage to the central nervous system. Sunstroke affects those who spend many hours in a row under the scorching rays of the sun with their heads uncovered. The meninges are warmed up.

Heat stroke occurs due to overheating of the body. It can happen to those who perform heavy physical work in a hot room or in hot weather. Heat strokes were especially common among our military personnel in Afghanistan.

In addition to actinometers for measuring infrared radiation, there are various types of pyramidometers. The basis of this action is the absorption of radiant energy by the black body. The receptive layer consists of blackened and white plates, which, depending on infrared radiation, heat up differently. A current is generated on the thermopile and the intensity of infrared radiation is recorded. Since the intensity of infrared radiation is important in production conditions, there are standards for infrared radiation for hot shops in order to avoid adverse effects on the human body, for example, in a pipe-rolling shop the bench is 1.26 - 7.56, iron smelting 12.25. Radiation levels exceeding 3.7 are considered significant and require preventive measures - the use of protective screens, water curtains, and special clothing.

Ultraviolet rays (UV).

This is the most biologically active part of the solar spectrum. It is also heterogeneous. In this regard, a distinction is made between long-wave and short-wave UV. UV promotes tanning. When UV enters the skin, 2 groups of substances are formed in it: 1) specific substances, these include vitamin D, 2) non-specific substances - histamine, acetylcholine, adenosine, that is, these are products of protein breakdown. The tanning or erythema effect comes down to a photochemical effect - histamine and other biologically active substances contribute to vasodilation. The peculiarity of this erythema is that it does not appear immediately. Erythema has clearly defined boundaries. Ultraviolet erythema always leads to a more or less pronounced tan, depending on the amount of pigment in the skin. The mechanism of tanning action has not yet been sufficiently studied. It is believed that first erythema occurs, nonspecific substances such as histamine are released, the body converts the products of tissue breakdown into melanin, as a result of which the skin acquires a peculiar shade. Tanning, therefore, is a test of the body's protective properties (a sick person does not tan, tans slowly).

The most favorable tanning occurs under the influence of UV rays with a wavelength of approximately 320 nm, that is, when exposed to the long-wavelength part of the UV spectrum. In the south, short-wave UFLs predominate, and in the north, long-wave UFLs predominate. Short-wavelength rays are most susceptible to scattering. And dispersion occurs best in a clean atmosphere and in the northern region. Thus, the most useful tan in the north is longer, darker. UFL are a very powerful factor in the prevention of rickets. With a lack of UVB, rickets develops in children, and osteoporosis or osteomalacia in adults. This is usually encountered in the Far North or among groups of workers working underground. In the Leningrad region, from mid-November to mid-February, the UV part of the spectrum is practically absent, which contributes to the development of solar starvation. To prevent sunburn, artificial tanning is used. Light starvation is a long-term absence of the UV spectrum. When exposed to UV in the air, ozone is formed, the concentration of which must be controlled.

UV rays have a bactericidal effect. It is used to disinfect large wards, food products, water.

The intensity of UV radiation is determined by the photochemical method by the amount of oxalic acid decomposed under the influence of UV in quartz test tubes (ordinary glass does not transmit UV light). The intensity of UV radiation is also determined by an ultraviolet meter. For medical purposes, ultraviolet radiation is measured in biodoses.