Parameter Tree:
EARTH SCIENCE > SUN-EARTH INTERACTIONS > IONOSPHERE/MAGNETOSPHERE DYNAMICS > AURORAE

Definition:
A faint visual phenomenon associated with geomagnetic activity,
which occurs mainly in the high-latitude night sky. Typical
auroras are 100 to 250 km above the ground. The phenomenon
caused by collisions between charged particles, atoms, and ions
in the Earth's ionosphere and upper atmosphere.


Reference:
NOAA/NGDC Solar-Terrestrial Gloassary
http://www.ngdc.noaa.gov/stp/GLOSSARY/glossary.html