tailieunhanh - Short-Wave Solar Radiation in the Earth’s Atmosphere Part 2

Nhiệt bức xạ của khí quyển trong phạm vi hồng ngoại là một ví dụ rõ ràng của quá trình này, mặc dù sẽ được hiển thị kế toán năng lượng tăng cường là thực sự quan trọng trong phạm vi sóng ngắn. | 20 Solar Radiation in the Atmosphere nl2 Y n and it is very suitable for the theoretical consideration as will be shown further. However it describes the real phase functions with a large uncertainty Vasilyev O and Vasilyev V 1994 . Therefore the using of this function needs a careful evaluation of the errors. The detailed consideration of this problem will be presented in Chap. 5. Radiative Transfer in the Atmosphere Within the elementary volume the enhancing of energy along the length dl could occur in addition to the extinction of the radiation considered above. Heat radiation of the atmosphere within the infrared range is an evident example of this process though as will be shown the accounting of energy enhancing is really important in the short-wave range. Value dEr - the enhancing of energy - is proportional to the spectral dA and time dt intervals to the arc of solid angle dQ encircled around the incident direction and to the value of emitting volume dV dSdl. Specify the volume emission coefficient as a coefficient of this proportionality dEr n J . dVdQdAdt Consider now the elementary volume of medium within the radiation field. In general case both the extinction and the enhancing of energy of radiation passing through this volume are taking place Fig. . Let I be the radiance incoming to the volume perpendicular to the side dS and I di be the radiance after passing the volume along the same direction. According to energy definition in incoming energy is equal to E0 IdSdQdAdt then the change of energy after passing the volume is equal to dE dIdSdQdAdt. According to the law of the conservation of energy this change is equal to the difference between enhancing dEr and extincting dEe energies. Then taking into account the definitions of the volume emitting coefficient and the volume extinction coefficient we can define the radiative transfer equation dI ai . dl In spite of the simple form is the general transfer equation with .