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Liquid water and ice emit radiation at a higher rate than water vapour (see graph above). Water at the top of the troposphere, particularly in liquid and solid states, cools as it emits net photons to space. Neighboring gas molecules other than water (e.g. nitrogen) are cooled by passing their heat kinetically to the water.
Nonthermal sources can have very high brightness temperatures. In pulsars the brightness temperature can reach 10 30 K. [9] For the radiation of a helium–neon laser with a power of 1 mW, a frequency spread Δf = 1 GHz, an output aperture of 1 mm 2, and a beam dispersion half-angle of 0.56 mrad, the brightness temperature would be 1.5 × 10 10 ...
Underwater vision is the ability to see objects underwater, and this is significantly affected by several factors. Underwater, objects are less visible because of lower levels of natural illumination caused by rapid attenuation of light with distance passed through the water. They are also blurred by scattering of light between the object and ...
The total amount of energy received at ground level from the Sun at the zenith depends on the distance to the Sun and thus on the time of year. It is about 3.3% higher than average in January and 3.3% lower in July (see below).
Output of a computer model of underwater acoustic propagation in a simplified ocean environment. A seafloor map produced by multibeam sonar. Underwater acoustics (also known as hydroacoustics) is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries.
[3] [4] [5] He was first to state that the incident ray, the reflected ray, and the normal to the surface all lie in a same plane perpendicular to reflecting plane. [6] [7] Specular reflection may be contrasted with diffuse reflection, in which light is scattered away from the surface in a range of directions.
In geophysics, most atmospheric gases, including the greenhouse gases, allow the Sun's short-wavelength radiant energy to pass through to the Earth's surface, heating the ground and oceans. The absorbed solar energy is partly re-emitted as longer wavelength radiation (chiefly infrared radiation), some of which is absorbed by the atmospheric ...
The optical depth of the atmosphere can be measured with a Sun photometer. The optical depth with respect to the height within the atmosphere is given by [ 3 ] τ ( z ) = k a w 1 ρ 0 H e − z / H {\displaystyle \tau (z)=k_{\text{a}}w_{1}\rho _{0}He^{-z/H}} and it follows that the total atmospheric optical depth is given by [ 3 ] τ ( 0 ) = k ...