ABC's of Science by Charles Oliver

CHAPTER VII
MISCELLANEOUS

1.
Lightning is caused by the friction of vapor, which is at a suitable
temperature. Thus two or more currents of air coming together will
cause lightning, as the friction concentrates the electricity, and as
there is no conductor the heavy voltage flies usually toward the
nearest conductor. This voltage is so great that it explodes the air.
The air coming together again produces a great vibration, called
thunder.

2.
Aurora Borealis. The outer circle around the earth represents
atmosphere. The sun current carries it far from the earth's surface.
At the north, when the sun's reflection strikes the earth's crust in
such a manner, its reflection will be seen in the atmosphere at a
great height, called Northern Lights. This is mostly seen in
November, December, and January.

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interesting read