Some factors determine the amount of UV radiation that reach certain part of Earth's surface. They are listed and briefly explained below:
• Cloud coverage. Water molecules on clouds scatter the radiation, hence the more clouds the less UV radiation.
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• Ozone. Similarly as cloud coverage, the more concentration of ozone the less UV radiation that reaches the surface of the Earth.
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• Angle of incidence. If the angle of incidence of the UV light is oblique the light will spread in a wider area, and hence the intensity is spread across this area.
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• Aerosols. The molecules of aerosols also scatter the UV light.
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• Elevation. The more the elevation the greater the amount of UV light.