What is the Ionosphere?
The ionosphere is defined as the layer of the Earth’s atmosphere that is ionized by solar and cosmic radiation. Short wave radiation that penetrates the Earth’s atmosphere does not reach the surface. A few examples of short wave radiation are x-rays, ultraviolet and gamma rays. When these waves pass through the atmosphere, they ionize molecules of oxygen and nitrogen and create a thin ionized region known as the ionosphere.
The short wave radiation is emitted from the Sun’s upper atmosphere, called the Corona. The Corona is very hot and produces a constant stream of radiation. During a 24 hour cycle the ionosphere will diurnally change it strength. The day side of the ionosphere will have multiple layers, thickening up as solar radiation ionizes it. The night side however will have a limited number of layers, produced by cosmic radiation.
The ionosphere is very important because it can be used to help transmit radio waves across the globe. The radio waves are able to bounce off the ionosphere for communication purposes.
The layers within the ionosphere are labelled with the Letters D, E, F1, F2, G. Each layer can reflect radio waves and the thicknesses of the ionized layers changes throughout the day. Layer G has the highest electron density and is the most ionized. The D region disappears during the night compared to the daytime and the E region becomes weakened.
During a solar flare, X-ray energy increases the ionization of all the layers, including the D layer. This can affect the behaviour of radio waves during the night as the radio waves won’t travel as far. Lightning can change where radio waves bounce. During the day lightning has little effect on the ionized layers, however at night time when there is a shortage of solar radiation, lightning can change where radio waves are bounced.