What does ionosphere mean?
The ionosphere is a region of the Earth's upper atmosphere, beginning at roughly 60 kilometres above the surface, where ultraviolet radiation and other forms of solar energy have stripped electrons from gas atoms and molecules. The resulting charged particles are called ions. Although the ionosphere has no sharply visible boundary, it contains layers whose density and behaviour vary with altitude, time of day, season, solar activity, and other conditions. These layers influence radio propagation by allowing some frequencies to travel long distances, while also creating conditions in which signals can be reflected, absorbed, or disrupted. The term is widely used in atmospheric science, astronomy, telecommunications, satellite operations, and space-weather forecasting. It should not be confused with the thermosphere, a neighbouring upper-atmospheric layer defined primarily by temperature rather than ionization.
nounThe region of the upper atmosphere, extending from roughly 60 to 1,000 kilometres above Earth, in which solar radiation has ionized most of the gas molecules. It forms several distinct layers, including the D, E, F1, and F2 layers.
- The ionized region of the upper atmosphere, between approximately 60 and 1,000 kilometres above Earth's surface.
- Any of the distinct layers within this region, especially those used to describe radio propagation or space-weather effects.
"Radio signals can travel long distances by reflecting off layers in the ionosphere."
"Solar activity can cause disturbances in the ionosphere and interfere with shortwave radio communication."
"The satellite passed through the upper ionosphere while collecting measurements of charged particles."
The plural is used when referring to the ionized regions of different planets or to multiple distinct ionospheric layers.
"The ionospheres of Earth and Mars respond differently to changes in solar wind."
The ionosphere is an invisible electric layer of the atmosphere that helps radio waves travel around the Earth.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ionosphere come from?
The word ionosphere combines ion with the suffix -sphere, a form of sphere denoting a spherical region. It was developed in the early twentieth century as scientific understanding of the ionized upper atmosphere advanced. The element ion comes from Greek, where it was associated with the electric charge carried by an atom or molecule, while sphere derives through Latin from Greek sphaira. Related terms such as ionic and ionization reflect the same scientific root.
Related word forms
How ionosphere is actually used
Usually used in scientific, technical, and communications contexts. In meteorology and space science, it refers to a region defined by ionization rather than simply by altitude.
Easily confused with ionosphere
The ionosphere is defined by the presence of ionized particles, whereas the thermosphere is defined by the temperature regime in a layer of the upper atmosphere; the two regions overlap but are not interchangeable.