The correct answer is Option 4: Ionosphere.
The ionosphere is the layer of the Earth`s atmosphere located between approximately 60 kilometers (37 miles) and 1,000 kilometers (621 miles) above the Earth`s surface. It is named after the ions that are present in this region. The ionosphere is responsible for the deflection of radio waves due to its unique properties.
Radio waves are a form of electromagnetic radiation used for communication and broadcasting purposes. When radio waves pass through the ionosphere, they encounter charged particles such as ions and free electrons. These charged particles interact with the electromagnetic field of the radio waves, causing them to be deflected or refracted.
The ionosphere consists of several distinct layers, each with different ionization characteristics. The most significant layer for radio wave deflection is the F layer (also known as the Appleton–Barnett layer), which is located at an altitude of approximately 150-400 kilometers (93-249 miles). The F layer is further divided into two sublayers: F1 and F2.
The F layer of the ionosphere contains a high concentration of ions and free electrons due to the absorption of high-energy ultraviolet radiation from the Sun. The presence of these charged particles allows the F layer to reflect or refract radio waves back to the Earth`s surface. This phenomenon is known as ionospheric reflection.
Ionospheric reflection is especially important for long-distance communication. By bouncing radio waves off the ionosphere, it is possible to transmit signals over the horizon and reach distant locations that are beyond the line of sight. This property of the ionosphere is utilized in long-range radio communication systems, such as shortwave radio and amateur radio.
Furthermore, the ionosphere`s ionization levels vary throughout the day and are influenced by various factors, including solar activity and the Earth`s magnetic field. These variations can affect the behavior of radio waves, causing changes in their propagation and interference patterns. This phenomenon is known as ionospheric propagation.
In conclusion, the ionosphere, specifically the F layer, is responsible for the deflection of radio waves due to its ionization properties. It plays a crucial role in long-distance communication by reflecting or refracting radio waves back to the Earth`s surface.