Space Weather A Research Perspective (1997) / Chapter Skim
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Space Weather: Glossary
Space Weather: Glossary
Pages 82-94
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From page 82... ...
The mean diameter of the oval is roughly 4000 km, but it expands toward the equator during magnetically disturbed periods, when the aurora also becomes brighter, and it contracts poleward during magnetically quiet periods. charge neutrality: A condition that within a region of space the number of positive charges is equal to the number of electrons.
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From page 83... ...
These are shaped by the coronal magnetic field structure. cosmic rays: Energetic particles with very high energies.
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From page 84... ...
electromagnetic radiation: Radiation carried by combined electric and magnetic fields that propagate at about the speed of light. Radio waves, infrared radiation, light, ultraviolet radiation, xrays, and gamma rays are all forms of electromagnetic radiation.
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From page 85... ...
The global electrical circuit includes regions of thunderclouds, which tend to drive current upward and charge the ionosphere positively, as well as fair-weather regions where the positive charge leaks back to the ground. Electrodynamic processes in the ionosphere and magnetosphere also influence the circuit.
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From page 86... ...
It includes the Sun itself as well as the corona and solar wind, and extends beyond the orbit of Pluto to distances in excess of 50 AU. heliospheric current sheet: A surface in the solar wind where there is a flow of electrical current that separates regions of oppositely directed interplanetary magnetic field.
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From page 87... ...
Ionization can be caused by the absorption of electromagnetic radiation or by a "collision" with a sufficiently energetic particle. ionosphere: The layer of Earth's upper atmosphere that is partially ionized by solar x-rays and ultraviolet radiation and energetic particles from space.
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From page 88... ...
Charged particles can move freely along magnetic fields, but may circulate around them rather than crossing them. magnetic or geomagnetic storms: Periods when the magnetic field measured on Earth is highly disturbed, radiation environments intensify, auroras are produced, and electrical currents are enhanced in the ionosphere and induced in the ground.
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From page 89... ...
particle precipitation: The release of charged particles stored in Earth's magnetosphere into the atmosphere. The particles follow magnetic field lines, and when they strike the atoms of the upper atmosphere, they cause them to glow like a giant television screen, creating the aurora (northern and southern lights)
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From page 90... ...
. radiation belt: The Van Allen radiation belt of Earth or other similar trapped energetic particle regions at other planets having magnetic fields.
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From page 91... ...
ahead of an obstacle, when the obstacle speed is faster than the speed of waves in the medium. The "bow shock" stands in front of the magnetosphere, and interplanetary shocks precede fast coronal mass ejections as they travel from the Sun.
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From page 92... ...
solar flare: An abrupt release, from a localized region on the Sun, of large amounts of energy in ultraviolet light, x-radiation, and occasionally gamma radiation. Flares usually occur in or near complex sunspot regions and may be related to the rearrangement of the intense magnetic fields there.
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From page 93... ...
dynamic reconfiguration of the magnetosphere in which energy stored in the magnetic field is converted into charged-particle energy. The process involves enhanced auroral emissions, strong disturbances in the highlatitude magnetic field, and the sudden appearance of increased numbers of energetic particles in the magnetosphere.
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From page 94... ...
USAF: United States Air Force. Van Allen radiation belts: A donut-shaped region in Earth's magnetosphere that contains a high density of energetic charged particles trapped in the dipole field of the planet.
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