Seasons - (n.)
The seasons in the middle and high latitudes depend on the variation in sunlight received throughout the year, as a result of the inclination of Earth's axis relative to the orbital plane. At northern summer solstice, the north pole of the Earth’s axis points toward the Sun, so that the Sun reaches its highest noontime position in the northern sky, being directly overhead at 23.5°N, at the tropic of Cancer. The day of northern summer solstice has the longest daylight in the year in the northern hemisphere, with the shortest night. At winter solstice, the north pole of the axis points away from the Sun, and the Sun reaches its lowest noontime position in the northern sky, being directly overhead at 23.5°S, at the tropic of Capricorn. The day of northern winter solstice has the shortest daylight on the northern hemisphere, and the longest night in the year. At equinox, the Sun is directly overhead at noontime on the Equator. The equinox following winter is called spring equinox, the one following summer is the fall equinox. During equinox, day and night are exactly of equal length everywhere on Earth. The seasons on northern and southern hemispheres are exactly opposite. The tropic of Cancer and the tropic of Capricorn get their names from a time when summer and winter solstice were reckoned by following the path of the Sun through the constellations of the zodiac, in the sky, rather than by looking in a printed calendar, as we do now. Though no longer the case, at that time the Sun was in the constellations Cancer and Capricorn during northern summer and winter solstice, respectively. (Puzzle: When was that?) Questions to ask yourself: How high above the horizon is the Sun at noon in Boulder, Colorado, on the day of northern summer solstice (Hint: Boulder is at 40°N.)? What about Oslo, Norway? From where can the midnight sun be seen on that day? How high above the horizon is the Sun at noon, in Boulder, on the day of northern winter solstice? What about Oslo, Norway? From where can the midnight sun be seen on that day?