Aurorae usually occur high above the clouds. The auroral glow [ http://www.geo.mtu.…] is created when fast-moving particles ejected [ http://antwrp.gsfc.…] from the Sun [ http://www.nineplan…] impact air molecules high in the Earth's atmosphere [ http://csep10.phys.…]. An oxygen molecule [ http://pearl1.lanl.…], for example, will glow in a green light when reacquiring an electron [ http://www.aip.org/…] lost during a collision with a solar particle. The lowest part of an aurora [ http://www.rog.nmm.…] will typically occur at 100 kilometers up, while most clouds [ http://www.cloudysk…] usually exist only below about 10 kilometers. The relative heights of clouds and aurorae are shown clearly in the above picture [ http://www.iww.is/a…] from Iceland [ http://www.cia.gov/…], where aurorae are relatively common. Over the past weekend, one of the largest sunspot groups [ http://www.sunspot.…] ever recorded has been associated with explosive solar activity [ http://antwrp.gsfc.…] and expansive terrestrial aurora displays [ http://apod.gsfc.na…AND Earth ]. Although in Earth's northern hemisphere aurorae [ http://www.pfrr.ala…] are usually seen only in the far north, these aurorae [ http://www.spacewea…] were so prevalent they were imaged by a continuous nighttime camera [ http://concam.net/k…] operating in southern Arizona [ http://www.state.az…]!
Explanation
Aurorae usually occur high above the clouds. The auroral glow [ http://www.geo.mtu.…] is created when fast-moving particles ejected [ http://antwrp.gsfc.…] from the Sun [ http://www.nineplan…] impact air molecules high in the Earth's atmosphere [ http://csep10.phys.…]. An oxygen molecule [ http://pearl1.lanl.…], for example, will glow in a green light when reacquiring an electron [ http://www.aip.org/…] lost during a collision with a solar particle. The lowest part of an aurora [ http://www.rog.nmm.…] will typically occur at 100 kilometers up, while most clouds [ http://www.cloudysk…] usually exist only below about 10 kilometers. The relative heights of clouds and aurorae are shown clearly in the above picture [ http://www.iww.is/a…] from Iceland [ http://www.cia.gov/…], where aurorae are relatively common. Over the past weekend, one of the largest sunspot groups [ http://www.sunspot.…] ever recorded has been associated with explosive solar activity [ http://antwrp.gsfc.…] and expansive terrestrial aurora displays [ http://apod.gsfc.na…AND Earth ]. Although in Earth's northern hemisphere aurorae [ http://www.pfrr.ala…] are usually seen only in the far north, these aurorae [ http://www.spacewea…] were so prevalent they were imaged by a continuous nighttime camera [ http://concam.net/k…] operating in southern Arizona [ http://www.state.az…]!
