Auroral colours are elemental signatures. Oxygen between roughly 100 and 250 km emits the familiar green line at 557.7 nm; thinner oxygen at 200 to 400 km gives the deep red 630.0 nm; nitrogen tints the lower fringe violet-pink near 427.8 nm. The stronger the solar wind, the more energy is fed in, so the auroral oval swells down towards lower latitudes while the Kp index climbs. A substorm dumps the magnetotail’s stored energy all at once, and the curtains flare and dance for some 30 to 60 minutes.
Auroral colours are elemental signatures. Oxygen between roughly 100 and 250 km emits the familiar green line at 557.7 nm; thinner oxygen at 200 to 400 km gives the deep red 630.0 nm; nitrogen tints the lower fringe violet-pink near 427.8 nm. The stronger the solar wind, the more energy is fed in, so the auroral oval swells down towards lower latitudes while the Kp index climbs. A substorm dumps the magnetotail’s stored energy all at once, and the curtains flare and dance for some 30 to 60 minutes.
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