In recent years, the haze weather has become more and more serious, and it has caused widespread concern around the world. Due to the reduced visibility of smog weather, which seriously affects the safety of travellers and drivers, road lighting design must take into account the haze weather factors. Therefore, the choice of suitable light source has become the most important and fundamental element of smog weather lighting design.
Reasons for reduced lighting in foggy weather conditions
In the smoggy weather, the air is rich in dust and water vapor, which scatters the light, causing the lighting effect of the lamp to decrease.
Penetration performance of light in smog
The penetration of light in air is determined by the scattering effect of the particles. Rayleigh and Mie scattering theory are two widely accepted theories that primarily analyze the scattering effects of particles of different sizes. The scattering effect of molecules and very small particles (<1/10 light wavelength) is determined by the wavelength of light, which falls within the scope of Rayleigh scattering theory. The particle diameter is larger than the wavelength of light, and Mie scattering dominates, and it has no connection with the wavelength of light. The diameter of dust and water vapor is much larger than the wavelength of 1/10 light, which indicates that light scattering in haze weather is only determined by the Mie scattering theory, and the wavelength of light does not affect the light penetration performance. Refer to the figure below for details.
Therefore, under smoggy weather conditions, the light penetration performance is independent of the wavelength and color temperature of the light.
Key factors for lighting in haze weather conditions
Safety issues have always been a primary consideration in lighting design, especially in road lighting design. As discussed in this paper, the wavelength and color of light have no effect on the illumination effect under haze weather conditions, so the color rendering index becomes an important indicator for the evaluation of lighting effects. In smoggy weather, colored objects are easily found on a white background, so high-color-reducing illumination is safer and more visible.
Why do people often think that red and yellow light is better in foggy weather?
According to the analysis of point 2 above, this conclusion is obviously wrong, which is based on the misunderstanding of Rayleigh scattering theory. In traditional applications, high-pressure sodium lamps are often considered the best choice for smog lighting because their deep yellow light contrasts sharply with the surrounding white haze. However, its lighting effect is not satisfactory. The figure below illustrates that red, green, and yellow are more pronounced on a white background than other colors.
Conclusions and recommendations
According to the above discussion, the lighting effect in the haze weather is not determined by the wavelength and color temperature of the light source, and a good color rendering index will contribute to a significant improvement in the lighting effect. In addition, due to the low color temperature of the lamp
Light is easy to spot, which will serve as a signalling light to help early warning of pedestrians and drivers, and the presence of dangerous or complex environments ahead.
Therefore, the conclusion of this paper is that in the smog weather conditions, to achieve the desired lighting effect, it is necessary to select an illumination source with a high color rendering index and a low color temperature.18V AC DC wall plug switching power adapter was widely used for any small power device, such as CCTV Cameras, wireless routers, LED strip, ADSL cats, HUB, switches, security cameras, audio/video power supply. For 18V wall mount power supply, the maximum output current is 2A,total 36W output. Our power adaptor meets different certificates for different countries` request – like UL list/CCC-CQC/ PES/SAA/C-TICK/CB/GB certificate. All our switching power supplies were getting 2-hours burn-in test & 3KV high voltage test during production.
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