Summer is one of the seasons of the year that begins, in the northern countries, on the day that the Sun enters the sign of Cancer, and ends when it exits Virgo. See Season and Sign.

Speaking more exactly and more generally, summer begins the day on which the meridian distance of the sun to the zenith is the smallest, and ends when the distance is precisely between the greatest and the smallest. See Sun.

The end of summer corresponds to the beginning of autumn. See Autumn.

From the beginning of summer up until that of autumn, the days are longer than the nights; but they always grow shorter as they go by, and are finally equal to the nights at the beginning of autumn.

The first day of summer being the one on which the Sun’s rays dart downward most directly, this should naturally be the day of the greatest heat; however, it is ordinarily towards the end of August, that is in the middle of summer , that we feel the greatest heat; this comes from the length of the days and the brevity of the summer nights, which causes the Sun’s heat given to the earth in the daytime, to subsist still more in part into the beginning of the next day, and to add in this way to that [heat] which the Sun gives off once again. Heat conserved in this way over several consecutive days, creates towards the middle of summer the greatest heat possible. See Heat.

We call rising and setting of summer [ [1]] the point on the horizon where the Sun rises and sets on the summer solstice. These points are more north than the east and west points on the horizon, which are the rising and setting of the equinoxes.[ [2]] See East, West, Orient, Occident.

Summer Solstice, see Solstice.

Translator's Notes

1. [The French terms referred to in D’Alembert’s Encyclopédie article, “levant d’été” and “couchant d’été” literally mean “rising of summer” and “setting of summer,” respectively, on the summer solstice or sunrise and sunset on the summer solstice (first day of summer in the Northern Hemisphere). “Levant” refers to the east and sunrise while “couchant” refers to the west and sunset. In particular, these terms refer specifically to where the sun is positioned on the horizon at sunrise and sunset on the summer solstice , “levant d’été” (summer solstice sunrise) being the sun’s extreme north position along the east horizon and “couchant d’été” (summer solstice sunset) being the sun’s extreme north position along the west horizon. On the winter solstice (first day of winter in the Northern Hemisphere), the sun rises and sets at the extreme south point along the east and west horizons, respectively.]

2. [The sun rises and sets on the vernal and autumnal equinoxes (late March and late September, respectively, in the Northern Hemisphere) exactly at the east and west horizon points (due east, due west). The following online material is helpful in gaining a broader understanding of the dynamics of seasonal transformations: see , for example, James B. Kaler’s article, “Measuring the Sky: A Quick Guide to the Celestial Sphere,” Web: 18 March 2011 http://stars.astro.illinois.edu see, also, the following Websites: http://solar.physics.montana.edu and http://curious.astro.cornell.edu.]