The screening of ultraviolet radiation is important to life on Earth. K. An object would not get very hot, however, in this layer because heating depends on the number of collisions between atmosphere atoms and the objects. These collisions would be more infrequent in the low density thermosphere. The concentration of ions and their velocities in the ionosphere are stongly affected by the solar wind and changes with the sunspot cycle. The state of the ionosphere affects the reflectivity of Earth radio waves.
Most atmospheres have some opacity, meaning portions of the visible spectrum are absorbed.
The absorption heats the atmosphere. C. Scattering properties 1. Blue sky . On Mars, the reddish-tan appearance of its sky is the result of micron sized dust particles suspended in its atmosphere. At sunset , the sky appears reddish because the blue portion has been subtracted by scattering at all angles away from the observer by the long path through the atmospheric aerosols.