1. Plural of ionosphere; regions of Earth's atmosphere containing ionized gases that reflect radio waves and are important for long-distance radio communication.
Usage: technical; usually used in plural when referring to multiple layers or regions

Examples

• Radio signals bounce off the ionospheres to reach distant receivers.
• Scientists study the ionospheres to understand how solar activity affects communications.
• The ionospheres extend from about 60 to 1,000 kilometers above Earth's surface.
• Auroras occur when charged particles interact with the ionospheres.
• Different ionospheres reflect different frequencies of radio waves.