SUMMER

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SUMMER ; in the northern hemisphere, the season comprehended in the months of June, July, and August; the warmest period of the year. South of the equator, the summer corresponds, in time, to our winter. The entire year is also sometimes divided into the summer, or warm season, and the winter, or cold season. The astronomical summer begins, in the northern hemisphere, when the sun has reached its greatest northern elevation,o therefore about June 21,and ends when it crosses the equator the second time in the year, about September 23. Notwithstanding the changes in the signs of the ecliptic, produced by the precession (q. v.) of the equinoxes, the ancient signs of summer have remained in the calendar. In the northern hemisphere, they are Cancer, Leo, Virgo ; in the southern, Capricorn, Aquarius, Pisces. Our summer takes place at the time when the earth is at the greatest distance from the sun, and hence moves the slowest. The diameter of the sun, therefore, appears considerably smaller at this season than in winter, and the summer of the northern hemisphere has ninetythree and a half days,a few days more than the winter, and, therefore, more than the summer of the southern hemisphere. Notwithstanding the greater distance of the sun in summer, his rays have much more effect than in winter, because they fall more directly upon the northern hemisphere. He also rises much sooner, and sets much later, and, therefore, describes a much greater arc in the heavens than in whiter. At the time when he has reached the tropic of Cancer, he ascends highest in the heavens, and remains longest above the horizon ; and we might, therefore, suppose that this would be the period of the greatest heat. But experience shows that the greatest heat generally takes place in August, throughout the whole northern hemisphere, far beyond the polar circle. The reason of this circumstance is, that, in August, the influence polar circle, as far as to the tenth or twelfth degree from the pole, the ice has been thawed and the temperature of the air moderated ; hence the wind which blows from those northern regions to tne south is milder.See Meyer's Manual of Physical Astronomy, Theory of the Earth, and Meteorology (German, Gottingen, 1805).