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Namangan Institute of Engineering and Technology
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Bog'liq ТўпламNamangan Institute of Engineering and Technology
nammti.uz
10.25.2023
Pg.14
The weakening of radiation in the atmosphere occurs due to changes in its spectral
composition. Depending on the height at which the sun is located relative to the horizon, the path
of solar rays in the atmosphere is quite large, and its maximum deviation occurs within 30 degrees
of the zenith. (Figure 2)
Figure 1 Figure 2
In the second figure, curve 1 corresponds to the spectrum of an absolute black body, with its
maximum at approximately 470 nm wavelength, allowing us to determine the temperature on the
sun's surface based on Wien's law - it is equal to 6100 K. Curve 2 contains several absorption lines,
with its maximum located near 555 nm. The intensity of radiation directly from the sun is measured
using a radiometer. The working principle of the radiometer is based on the absorption of the
incident radiation by the absorbing surfaces exposed to the solar radiation. Determining the
spectrum of solar radiation is also based on the values of the absorbance index in the attenuating
environment. The absorbance index of the environment (or atmosphere) depends on the absorption
wavelength (or frequency) of light because light at different wavelengths is attenuated at different
rates in the same environment. Therefore, a single environment selectively attenuates various
monochromatic lights. The dependence of the absorbance index of the environment on the
wavelength of light is called the dispersion of light (dispersion indicates a kind of spreading). In other
words, the dispersion of solar light refers to the separation of the spectrum due to interference or
diffraction in the passage of light. Depending on the decrease in the wavelength of light, the
absorbance index is also reduced, then it is called normal dispersion; otherwise, it is referred to as
anomalous dispersion. Transparent and colorless environments (meaning environments with low
light absorption) have the property of normal dispersion (they strongly attenuate violet (short-
wavelength) light). Anomalous dispersion can occur in colored environments; due to dispersion,
when passing through an environment that absorbs solar light (visible light), it separates into various
monochromatic lights. These separated lights create a dispersion spectrum - an array of various
colored paths (bands). In the form of a gaseous state, for example, when passing through a prism,
the solar light spectrum with continuous bands due to dispersion is clearly visible (Figure 3).
Figure 3
In Figure 3, the dispersion of solar light through a glass prism is depicted. The glass, having
normal dispersion, causes the light of different colors to deviate from their original path, with the
violet light deviating the most and the red light deviating the least. The angle of deviation, D,
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