1/25/2024 0 Comments Layers of the earth 3d modelThis factor, together with the lower temperatures on Mars, reduces the absorptivities and emissivities enough to make the CO 2 atmospheric warming effect on Mars weaker than that on Earth. However, the collisional broadening of the CO 2 absorption and emission lines in the thin Martian atmosphere is much less than on Earth. The amount of CO 2 in a column of the Martian atmosphere is about 17 times greater than in a similar column of Earth’s atmosphere. The atmosphere of Mars, at a total pressure of 0.64 kPa (about 1/160 that of Earth), is 95% CO 2. Thus the absorptivity and emissivity at this wavelength will decrease with altitude. A wavelength that is absorbed relatively strongly in the broadened wavelength range at lower altitudes will absorb more weakly at higher altitudes where the broadening is less. Thus, line broadening for IR-absorbing gases is larger at lower altitudes and decreases with altitude. Any collision can cause this perturbation, so the amount of the line broadening is a function of the total pressure or density of the gas, including both IR-absorbing and non-absorbing molecules. Perturbation of the energy of an absorbing or emitting molecule during a collision with another molecule leads to a broader spread of absorbed or emitted wavelengths than for the undisturbed molecule. Finally, we must account for the effects of collisional absorption-emission line broadening. Emissivity is also temperature dependent, decreasing with decrease in temperature. The absorptivity (and therefore the emissivity) of the layers decreases with altitude for several reasons, the most obvious being the decrease in numbers of IR-absorbing molecules as the density of the atmosphere decreases.
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