Final answer:
When electromagnetic waves move upward from an antenna, some waves pass through, some are absorbed, some are reflected by atmospheric layers like the ionosphere, and some get scattered in all directions depending on their frequencies and atmospheric conditions.
Step-by-step explanation:
When electromagnetic waves emitted from an antenna move upward and away into the atmosphere, several things can happen:
- Some of the waves pass through the atmosphere without significant alteration, particularly if the material is transparent to their frequency.
- Others can be absorbed by the atmosphere, which tends to occur when there is an interaction between the wave and molecules in the air, resulting in phenomena like thermal agitation.
- Another portion of the waves can be reflected back towards Earth, especially if they encounter layers of the atmosphere that are opaque to their frequencies, such as the ionosphere for certain types of radio waves.
- Electromagnetic waves can also be scattered in all directions depending on the atmospheric conditions and the wavelength of the waves.
High-frequency waves often do not reach the Earth's surface and must be observed from space, while certain low-frequency waves like FM and TV can travel easily through the atmosphere. AM radio waves, however, might be reflected by the ionosphere.