By shape:
* Arcs: The most common aurora shape, appearing as long, curved bands of light.
* Bands: Similar to arcs, but wider and more diffuse.
* Rays: Long, vertical streaks of light.
* Veils: Thin, sheet-like curtains of light.
* Patches: Irregular, blotchy patches of light.
* Corona: A circular aurora, appearing as a crown of light.
By color:
* Green: The most common aurora color, caused by excited oxygen atoms.
* Red: Occurs at higher altitudes, also caused by excited oxygen atoms.
* Blue: Caused by excited nitrogen molecules.
* Purple: A combination of red and blue.
* White: A mixture of all colors, often seen in very intense auroras.
By location:
* Aurora Borealis (Northern Lights): Occurs in the Northern Hemisphere.
* Aurora Australis (Southern Lights): Occurs in the Southern Hemisphere.
By intensity:
* Sub-visual: Too faint to be seen by the naked eye.
* Diffuse: Weak, faint aurora.
* Discrete: Bright and defined aurora.
By activity:
* Quiet: A period of low aurora activity.
* Active: A period of moderate aurora activity.
* Storm: A period of intense aurora activity.
By altitude:
* Lower aurora: Typically occurring at altitudes of 80-150 km (50-93 miles).
* Higher aurora: Typically occurring at altitudes of 150-400 km (93-249 miles).
By cause:
* Auroral substorms: Caused by sudden releases of energy from the magnetotail.
* Auroral storms: Caused by strong geomagnetic activity, often associated with solar flares or coronal mass ejections.
It's important to note that these classifications are not mutually exclusive, and an aurora can exhibit multiple characteristics at the same time. For example, a red, rayed aurora could be classified as both a "ray" and "red" aurora.
