Crossword-Solution: AUROR 5 letters, 1 clue 🏆 scrabble score: 5

Even the fact that somewhat fewer auroræ are seen in June than in December also finds its explanation in the known fact that the earth is about three million miles nearer the sun in the winter than in the summer, and the number of particles reaching it will vary, like the intensity of light, inversely as the square of the distance.

First, the number of auroræ, according to his explanation, ought to be greatest in the daytime, when the face of the earth on the sunward side is directly exposed to the atomic bombardment.

Observation shows, too, that auroræ are more frequent before than after midnight, which is just what we should expect if they originate in the way that Arrhenius supposes.

Second, the theory offers an explanation of the alleged fact that the formation of clouds in the upper air is more frequent in years when auroræ are most abundant, because clouds are the result of the condensation of moisture upon floating particles in the atmosphere (in an absolutely dustless atmosphere there would be no clouds), and it has been proved that negative ions like those supposed to come from the sun play a master part in the phenomena of cloud formation.

Similarly, gigantic solar waves may produce auroræ; and minute waves from a candle do electrically disturb the retina.