The ionosphere (also named the thermosphere) stays on a height of 80 till more then 500km.
The medium temperature is 400°C.
On the beginning from the ionosphere is the temperature -100°C and at the end more than 1000°C.
The ray of the sun makes a strong ionisering (that's an accumulation of many charged particles) which makes that this sphere conducts electronic very good.
Because of that ions conducts and reflects radio wave signals is broadcasting around the earth possible.
Without these charged particles would most of the radio waves disappear in space and was there no radio- and TV broadcasting possible which would be a nightmare for many of us.