Solar radiation.pptx

Solar radiation and its hygienic value

1. MINISTRY OF HEALTH OF UKRAINE DONETSK NATIONAL MEDICAL UNIVERSITY Solar radiation and its hygienic value BY: SRISHTI GUPTA GROUP: 603 A.M. KROPYVNYTSKYI 2023

2. Objectives to review the properties of solar radiation; to determine theoretical upper limit of solar radiation available at the earth’s surface; to determine the position of the sun in the sky and the beam radiation direction that is incident on surfaces of various orientations and shading. Hygienic and general biological meaning of solar radiation. The visible part of the solar spectrum and it’s effect on the body. Infrared radiation and the effect on the body. Ultraviolet radiation and it’s effect on the body.

3. Radiation: The transfer of energy via electromagnetic waves that travel at the speed of light. The velocity of light in a vacuum is approximately 3 x 108 m/s. The time it takes light from the sun to reach the Earth is 8 minutes and 20 seconds. Heat transfer by electromagnetic radiation can travel through empty space. Any body above the temperature of absolute zero (-273.15o C) radiate energy to their surrounding environment. The many different types of radiation is defined by its wavelength. The electromagnetic radiation can vary widely.

4. radio wave radiation infrared radiation visible radiation ultraviolet radiation X-ray radiation gamma rays

5. Solar Radiation Spectrum Visible light has a wavelength of between 0.40 to 0.71 micrometers (µm). The sun emits only a portion (44%) of its radiation in this range. Solar radiation spans a spectrum from approximately 0.1 to 4.0 micrometers. About 7% of the sun's emission is in 0.1 to 0.4 micrometers wavelength band (UV). About 48% of the sun's radiation falls in the region between 0.71 to 4.0 micrometers (near infrared : 0.71 to 1.5 micrometers; far infrared: 1.5 to 4.0 micrometers).

6. Solar radiation incident outside the earth's atmosphere is called extraterrestrial radiation. On average the extraterrestrial irradiance is 1367 W/m2. This value varies by ±3% as the earth orbits the sun.

7. Types of the solar radiation 1- Reflected and scattered clouds 2 – Straight or beam 3 - Absorbed 4 - Reflected

8. Direct solar radiation is radiation that comes to the earth's surfacedirectly from the Sun. On the Earth's surface, solar radiation comes from a beam of practically parallel rays and is characterized by the Intensity of radiation. Broken solar radiation is a part of solar radiation (about 25% -30%), which get dispersion in the atmosphere - transformed in the atmosphere from direct solar radiation into radiation traveling in all directions. The reason for the scattering of sunlight is the inhomogeneity (different density) of the air. Radiation spreads from the scattering particles of the air as if these particles were themselves a source of radiation.

9. Reflected solar radiation is part of the total solar radiation, which is not absorbed by the earth's surface, but is reflected from it. Depends on the nature of the reflection surface. Absorbed solar radiation is part of the total solar radiation, which is absorbed by the earth's surface and is used to heat the upper layers of the soil, water, and snow cover. The absorbed solar radiation I equal to the difference between the total and reflected radiation

10. Atmospheric Effects on Incoming Solar Radiation The Earth is a planet with an atmosphere and is largely transparent to the incoming solar radiation. There are constituents in the atmosphere which prevent some kinds of radiation from reaching the surface, such as ozone which stops the ultraviolet. A fair proportion of the Earth is covered by clouds which reflect a lot of the Sun's radiation and thus affecting the surface temperature

11. If intercepted, some gases and particles in the atmosphere have the ability to absorb incoming insolation. Absorption is defined as a process in which solar radiation is retained by a substance and converted into heat. The creation of heat also causes the substance to emit its own radiation. In general, the absorption of solar radiation by substances in the Earth's atmosphere results in temperatures that get no higher than 1800° C. Bodies with temperatures at this level or lower would emit their radiation in the longwave band. Further, this emission of radiation is in all directions so a sizable proportion of this energy is lost to space. The third process in the atmosphere that modifies incoming solar radiation is reflection. Reflection is a process where sunlight is redirect by 180° after it strikes an atmospheric particle. This redirection causes a 100 % loss of the insolation. Most of the reflection in our atmosphere occurs in clouds when light is intercepted by particles of liquid and frozen water. The reflectivity (albedo) of a cloud can range from 40 to 90 %.

12. Selective Absorption of the Atmosphere T he amount of energy carried by a photon depends on the wavelength. Thus the atoms that comprise a gas can only absorb, or emit, particular wavelengths of energy (i.e. photons of energy). We can see this selective absorption by examining Figure below. The graph shows very little absorption for atmosphere as a whole in the shortwave end of the spectrum, especially in the visible light band (the band of maximum emission for the Sun). The atmosphere absorbs far better in the long wave end of the electromagnetic spectrum which is the region of maximum emission (10µm) for the Earth.

13. Ultraviolet radiation General biological effect photochemical effect - the formation of biologically active substances, the effect on all types of metabolism (healing and toning effect) Specific effect erythemal tanning effect (400 - 320 nm) antirachitic (320 - 280 nm) bactericidal (280 - 200 nm) damaging (275 - 180 nm). Possesses low penetration

14. Hygienic and general biological significance of individual parts of solar radiation People who get Insufficient UV radiation like Northern people in winter, mining workers, people working in dark rooms like photographers children and adolescents Prevention of UV deficiency: solariums, sunbeds and sunbathing

15. Value of the visible part of the solar spectrum gives 80% of the information from the outside world. has a beneficial effect on the body stimulates the vital activity of the body increases metabolism improves overall health improves emotional mood increases efficiency has a thermal effect

16. Infrared radiation Shortwave (wavelength - 760-1 400 nm) high energy high penetrating power, As a result of reflex action, it increases: Body temperature, the pulse It takes a breath, The blood pressure is reduced expansion of gas exchange induced renal excretory function

17. Infrared radiation can promote local blood circulation and reduce muscle tension. Examples of traditional medical applications of infrared radiation include the relief of muscle pain and tension, as well as the treatment of autoimmune diseases or wound-healing disorders. Infrared (IR) light is used by electrical heaters, cookers for cooking food, short-range communications like remote controls, optical fibres , security systems and thermal imaging cameras which detect people in the dark.

18. Measuring Infrared radiation Actinometers Pyranometers Radiometers

19. “Light starvation” is a long exclusion of the action of natural UV-radiation on the skin, as a result of which hypo- or vitamin deficiency D develops, followed by impaired calcium-phosphorus metabolism.

20. Application methods: Direct exposure - is used only in the absence of people in the treated room. Indirect exposure (reflected rays) - used in the presence of people with restrictions on the time of operation. Closed irradiation (in ventilation systems and autonomous recirculation devices) - used in the presence of people with limited operating time.

21. INFRARED RADIATION Infrared rays are electromagnetic waves. It lies between visible light and microwaves. Wavelength: 750 nm to 400000 nm. Frequency: 4×1014 Hz and 7.5×1011 Hz Type Wavelength IRA - 760-1400 nm IRB - 1400-3000 nm IRC -3000nm –1mm

22. TYPES OF IR LAMPS Two types of infrared sources are used in physiotherapy practice: Non-luminous generators Luminous generators

23. THERAPEUTIC USES Relief of pain Muscle relaxation Increased blood supply Increase in joint mobility Acceleration of healing and repair

24. DANGERS Burns Electric shock Faintness or giddiness Headache Gangrene Injury to the eyes dehydration

25. DOSAGE For acute cases irradiation with infra-red rays can be given for 10 to 15 minutes daily for 1 to 3 times as per the requirement. For chronic cases up to 30 minutes once (daily) or on alternate days can be given.