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In contrast, if the entire Earth was covered by water – a so-called ocean planet – the average temperature on the planet would rise to almost 27 °C (81 °F). [ 19 ] In 2021, scientists reported that Earth dimmed by ~0.5% over two decades (1998–2017) as measured by earthshine using modern photometric techniques.
Another measure of reflectance, depending only on the outgoing direction, is I/F, where I is the radiance reflected in a given direction and F is the incoming radiance averaged over all directions, in other words, the total flux of radiation hitting the surface per unit area, divided by π. [2]
Planetlight is the diffuse reflection of sunlight from a planet, whose albedo can be measured. The most observed and familiar example of planetshine is earthshine on the Moon , which is most visible from the night side of Earth when the lunar phase is crescent or nearly new , [ 1 ] without the atmospheric brightness of the daytime sky.
In physics, backscatter (or backscattering) is the reflection of waves, particles, or signals back to the direction from which they came. It is usually a diffuse reflection due to scattering , as opposed to specular reflection as from a mirror , although specular backscattering can occur at normal incidence with a surface.
In ordinary light, the vibrations occur in all planes perpendicular to the direction of propagation. When light passes through a Nicol prism its vibrations in all directions except the direction of axis of the prism are cut off. The light emerging from the prism is said to be plane polarised because its vibration is in one direction. If two ...
Diagram showing displacement of the Sun's image at sunrise and sunset Comparison of inferior and superior mirages due to differing air refractive indices, n. Atmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of height. [1]
The ratio of waves' electric field (or magnetic field) amplitudes are obtained, but in practice one is more often interested in formulae which determine power coefficients, since power (or irradiance) is what can be directly measured at optical frequencies. The power of a wave is generally proportional to the square of the electric (or magnetic ...
In geophysics, shortwave flux is a result of specular and diffuse reflection of incident shortwave radiation by the underlying surface. [3] This shortwave radiation, as solar radiation, can have a profound impact on certain biophysical processes of vegetation, such as canopy photosynthesis and land surface energy budgets, by being absorbed into the soil and canopies. [4]