Fall, or autumn, marks a distinctive period, bridging the warmth of summer with the colder months of winter. It is characterized by noticeable shifts in the natural world and serves as a time of transition and preparation. Across various regions, this season is celebrated for its unique atmospheric qualities and the transformation of foliage.
Understanding the Season
Fall’s arrival is defined by two systems: astronomical and meteorological. Astronomical fall begins with the autumnal equinox, around September 22 or 23 in the Northern Hemisphere and March 20 or 21 in the Southern Hemisphere. This point signifies when the sun is directly over the equator, resulting in nearly equal day and night lengths. The season concludes with the winter solstice, typically around December 21 or 22 in the Northern Hemisphere and June 20 or 21 in the Southern Hemisphere.
Meteorological fall follows a fixed calendar schedule. In the Northern Hemisphere, it spans September, October, and November. In the Southern Hemisphere, meteorological fall encompasses March, April, and May. This period signals a decrease in daylight hours and a cooling of temperatures as the Earth’s hemisphere tilts away from the sun.
Why We Call it “Fall”
The term “fall” originated in the 16th century as a shortened form of phrases like “fall of the leaf” or “fall of the year,” referencing the shedding of leaves. This name became widely used in England before the 17th century, though it later became more common in North America, while “autumn” gained prominence in Britain.
The name “autumn” traces its heritage back to Latin. Derived from the Latin word “autumnus,” its use in English dates to the late 1300s. Before the widespread adoption of either “fall” or “autumn,” the season was often referred to as “harvest,” a term with Old English and Germanic roots.
Distinctive Seasonal Changes
As fall progresses, daylight hours decrease, and temperatures cool. These environmental cues prompt deciduous trees to prepare for winter dormancy, a remarkable transformation of their leaves. The vibrant green color characteristic of spring and summer foliage starts to fade as the dominant pigment, chlorophyll, breaks down. Chlorophyll is essential for photosynthesis, converting sunlight into food.
With the degradation of chlorophyll, other previously masked pigments become visible, including carotenoids responsible for the yellow and orange hues. Carotenoids are present in the leaves throughout the growing season. Additionally, some trees produce pigments called anthocyanins, which create striking red, purple, and crimson colors. Anthocyanins are typically produced in the fall in response to bright light and accumulated sugars within the leaves. The intensity and duration of these colors are influenced by weather conditions, with warm, sunny days followed by cool, non-freezing nights often leading to brilliant displays.
The Season’s Broader Impact
Fall, beyond its visual appeal, influences agricultural practices and cultural traditions worldwide. It is known as the harvest season, a time when many crops mature and are gathered before winter. This rhythm has shaped numerous celebrations and festivals.
Many holidays are deeply intertwined with the fall season:
In the United States and Canada, Thanksgiving is celebrated as a harvest festival, focusing on gratitude and communal feasts.
Halloween, observed on October 31, has roots in ancient Celtic festivals like Samhain, marking the end of the harvest.
Diwali, the Hindu festival of lights (Oct/Nov), symbolizing the triumph of good over evil.
The Mid-Autumn Festival, or Moon Festival, is celebrated in East Asian countries (Sept/Oct), emphasizing family reunions and moon gazing.
Oktoberfest in Germany (late Sept) is a festival centered around Bavarian culture and beer.
Mexico observes Día de los Muertos (Day of the Dead) in early November, a vibrant tradition honoring deceased loved ones.
Fall is a period of intense activity for animals as they prepare for the colder months. Many species engage in food hoarding, like nuts and seeds, to sustain them through winter scarcity. Some animals, such as bears and groundhogs, enter a state of hibernation or reduced activity, slowing their metabolism to conserve energy. Others, particularly many bird species, undertake long migrations to warmer climates where food remains abundant. Mammals also grow thicker coats of fur for insulation against dropping temperatures.