Summer officially gives way to fall Tuesday evening, ushering in a season of shorter days, cooler temperatures, changing leaves and, in Adams County, apple harvests and other familiar signs of autumn.
The autumnal equinox arrives at 8:04 p.m. EDT Tuesday, Sept. 22, marking the astronomical beginning of fall in the Northern Hemisphere. Meteorologists use a different definition, with meteorological fall beginning Sept. 1.
The equinox occurs when the center of the sun crosses the celestial equator, an imaginary extension of Earth’s equator into space. In the Northern Hemisphere, the September crossing marks the transition from summer to autumn.
Despite the meaning of the word equinox — derived from Latin words for equal and night — Tuesday will not have precisely 12 hours each of daylight and darkness. The way sunrise and sunset are measured, combined with the bending of sunlight through Earth’s atmosphere, means daylight remains slightly longer than 12 hours.
From this point until the winter solstice, daylight will continue to decrease as sunrises come later and sunsets arrive earlier. After the winter solstice, the days gradually begin growing longer again.
In Adams County, the arrival of fall coincides with one of the busiest periods of the agricultural year.
The season also brings pumpkins, corn mazes and other harvest activities. Plants and trees begin to slow their growth as sunlight decreases, while asters and chrysanthemums are among the flowers associated with the season.
Changing leaves are another unmistakable sign of fall, but cooler temperatures alone do not cause the transformation. The decreasing amount of daylight affects photosynthesis and plays a major role in producing autumn colors.
Fall will continue until the winter solstice in December, when the Northern Hemisphere experiences its shortest period of daylight.
Source: almanac.com