Abstract
Height measurements on the lower edges of homogeneous and rayed arcs and bands are reported from 404 photographs taken of aurorae over Churchill (58.8° N., 94.2° W.) during the winter of 1957–58 as part of the I.G.Y. programme. The frequency distribution in height of 1975 points measured shows a double peak at 101 and 107 km, and a mean height of 104.8 km. The chief factor affecting height of aurora appears to be that of intensity; the mean height of weak aurorae was found to be 107.7 km, while that of strong aurorae was 100.1 km. No difference in mean height of aurorae before and after midnight was observed. Tidal effects in the upper atmosphere did not appear to affect auroral height greatly. The mean heights of aurorae measured during high and low tide conditions showed no appreciable difference. A mean orientation of 105.5° magnetic azimuth was measured for auroral arcs. Auroral motions with speeds up to 2500 meters per second were observed.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
