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Stellar models predict a temperature of 15 MK in the center of the Sun, and at the cores of supergiant stars the temperature may exceed 1 GK. As the radiation pressure scales as the fourth power of the temperature, it becomes important at these high temperatures. In the Sun, radiation pressure is still quite small when compared to the gas pressure.
Figures 1 and 2 in A Preliminary communication on the pressure of heat and light radiation, Phys. Rev. 13, 307-320 (1901).. A Nichols radiometer was the apparatus used by Ernest Fox Nichols and Gordon Ferrie Hull in 1901 for the measurement of radiation pressure.
This approximation reduces the temperature by a factor of 0.7 1/4, giving 255 K (−18 °C; −1 °F). [ 29 ] [ 30 ] The above temperature is Earth's as seen from space, not ground temperature but an average over all emitting bodies of Earth from surface to high altitude.
The thermodynamics of a black-body photon gas may be derived using quantum statistical mechanical arguments, with the radiation field being in equilibrium with the atoms in the wall. The derivation yields the spectral energy density u, which is the energy of the radiation field per unit volume per unit frequency interval, given by: [3]
Isotherms of an ideal gas for different temperatures. The curved lines are rectangular hyperbolae of the form y = a/x. They represent the relationship between pressure (on the vertical axis) and volume (on the horizontal axis) for an ideal gas at different temperatures: lines that are farther away from the origin (that is, lines that are nearer to the top right-hand corner of the diagram ...
The radiation stress – mean excess momentum-flux due to the presence of the waves – plays an important role in the explanation and modeling of various coastal processes: [1] [2] [3] Wave setup and setdown – the radiation stress consists in part of a radiation pressure, exerted at the free surface elevation of the mean flow
This is related to radiation pressure tangential to the grain's motion. This causes dust that is small enough to be affected by this drag, but too large to be blown away from the star by radiation pressure, to spiral slowly into the star. In the Solar System, this affects dust grains from about 1 μm to 1 mm in diameter. Larger dust is likely ...
A Crookes radiometer in action. The radiometer is made from a glass bulb from which much of the air has been removed to form a partial vacuum.Inside the bulb, on a low-friction spindle, is a rotor with several (usually four) vertical lightweight vanes spaced equally around the axis.