[82]The different Phenomena of the Aurora Borealis may be owing to the Ascent and Motion of the Apogay, in the middle Region, over the Stratum of Eknèfiai or Ground-Winds.
The Effects of Tides in the Air yet to be mentioned, must not, however, be wholly excluded.
The Aurora Borealis is seen in Spring, Autumn, and Winter: sometimes culminating, sometimes moving in Streams and Waves in the superior Regions of the Atmosphere: when culminating; as if rising out of Clouds in the North.
This Appearance may be owing to warm moist Air perpetually generating between the Tropics, and rolling over the cold dry Stratum of Eknèfiai Winds, which cut off its Communication with the Earth: till accumulating over the Poles, it enlightens the Atmosphere, converting a six Month’s Night into Day; and returns to the Surface silently: or in Lightning, whenever it is communicated to the Earth, throu’ Vapour descending by its own specific Gravity; or along with depressing Torrents of Air, known to be accompanied by frequent flashes.
When the Vapour is condensed in its Descent, by passing throu’ a Stratum of the Eknèfiai Winds; it becomes overcharged with the electric Matter, surrounding and adhering to it; and deposits the Overplus in Lightning, on its Approach to other Clouds, or to the Earth.
It is visible in the Form of a Vapour, when the Vapour to which it adheres, becomes overcharged with electric Matter, by Descent into a cool Eknèfiai Stratum below: there forming a luminous and transparent Atmosphere: the Particles of Light and Vapour being repelled to great Distances from each other at so rare a Height.
It culminates above the Vapour, because less heavy than the circumambient Air: and may be subject to the Attraction of other Planets.
The Aurora Borealis is also seen to issue in Streams and Waves of Light, with inexpressible Velocity, on its Return to the South, in a lower Stratum, as it passes throu’ Interstices, between the Vesicles of warm Vapour, raised and dispersed by the turbulent Apogay Winds, in the middle Region.
During Summer, the middle Region becomes blended with the lower, throu’ Defect of Cold: and the electric Matter is supposed to be communicated to the Earth, silently, and continually; but by Lightning, when a lower and colder Atmosphere condenses and overcharges the Vapour, and cuts off the Communication.
It cannot be seen but in escaping from Vesicle to Vesicle: nor, during Summer, after Sunset, on Account of the Twilight.