The ionized part of the Earth’s atmosphere is known as the ionosphere. Ultraviolet light from the sun collides with atoms in this region knocking electrons loose. This creates positive ions, or atoms with missing electrons. This is what gives the Ionosphere its name and it is the free electrons that cause the reflection and absorption of radio waves.
During Day
When the sun is overhead during the day, most of the ionosphere is ionized due to the large amount of ultraviolet light coming from the sun. During the day, there are 4 layers: D, E, F1, and F2.
During Night
During the night, the ionosphere is weakened. layer D disappears, layer E weakens, and Layers F1 and F2 are combined to Layer F
