Sky radiation
This is otherwise known as the scatter radiation or scattered radiation. His presence is to increase the heat of the earth, in addition to those from direct radiation, and this follows from the transparent atmosphere.
Atmospheric losses in direct radiation, which produce sky radiation stem from four basic phenomena:
- Scattering of direct radiation in all directions, which occurs when the radiant energy meets real molecules ideal gases (oxygen and nitrogen) into the atmosphere. This effect is more pronounced for short waves, and accounts for the blue appearance of the sky.
- Scattering arising from the presence of water vapor molecules.
- Selective absorption of ideal gases and water vapor. Asymmetrical gaseous molecules, such as ozone, water vapor, carbon dioxide and others, have a great ability to absorb (and therefore emit radiation than do the gaseous molecules of a symmetrical patterns, such as nitrogen and oxygen, (iv) the Scattering caused by dust particles.
The losses incurred, mainly due to the permanent gases and water vapor.
There is also some diffusion direct sunlight caused by direct and indirect) detects the radiation clouds. Not all that solar energy is removed from direct radiation processes of scattering and absorption reaches the earth's surface. Some scattered back into space, and the absorbed energy that is re-radiated at longer wavelength (mainly water vapour) also partly lost in outer space. Some advanced direct energy lost by reflection from the upper surface of clouds. However, a lot of energy that direct radiation loses eventually reaches the earth's surface in a scattered form.
The amount of solar radiation depends on the time of day, weather, cloud cover and part of the sky, from which it is received, the amount of heaven in the vicinity of the sun, exceeding from other areas, for example. Sky radiation, however, cannot be assigned to a certain direction, and, therefore, he casts no directional shade outdoors.
The equation (see section 7.15) to calculate the total scattered solar radiation received from the sky and the earth. The intensity of this radiation is dependent on seasonal fluctuations in humidity and sun-earth distance (given Allen (1973), as 149.5 x 106 km), angular correlation to obtain a surface with respect to the environment, and reflectances of the corresponding surfaces.
The average daily radiation on sloping and flat surfaces under different angles to the horizon, both direct and diffuse solar radiation provided by CIBSE Guide A2 (1999). In several places are given, including Bracknell, over different orientations. The intensity of scattered radiation mainly depends on height of the sun, but also, to a lesser extent, the orientation when receiving a vertical surface...
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