As summer draws to a close, the anticipation for the fall season begins. The still-warm weather might suggest otherwise, but the official start of fall is just around the corner. While some may consider the back-to-school season as the beginning of autumn, there is a precise date that marks the official start. Let’s explore everything you need to know about the first day of fall, the autumnal equinox, and what this season brings.
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The Official Start of Fall: What You Need to Know
When is the first day of fall? The first day of fall is known as the autumnal equinox; this year, it falls on Sunday, September 22, 2024. The exact moment of the equinox will occur at 8:44 AM EDT in the Northern Hemisphere. This event signifies the astronomical beginning of the fall season.
But did you know there are two ways to define the start of fall? Besides the astronomical fall that begins with the equinox, meteorologists often consider September 1 as the start of meteorological fall, based on the annual temperature cycle.
Understanding the Autumnal Equinox
The autumnal equinox is one of two times a year when the Earth’s axis is tilted neither towards nor away from the Sun. This unique alignment results in nearly equal amounts of daylight and darkness. The other equinox that occurs in spring, is known as the vernal equinox.
The autumnal equinox is significant because it marks the transition from the longer days of summer to the shorter days of winter. After this day, the nights will continue to grow longer until the winter solstice.
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When Will the Leaves Start Changing?
One of the most anticipated events of fall is the changing of the leaves. The timing of this natural spectacle varies across the United States.
According to the 2024 fall foliage prediction map from SmokeyMountains.com, the first leaves will begin to change in early September along the Canadian border and in some northern states like Colorado and Utah. By October 30, nearly all of the contiguous U.S. will see the vibrant hues of fall, ranging from minimal to past peak colors.
What is the Autumnal Equinox?
The autumnal equinox is an astronomical event that occurs when the Sun crosses the celestial equator. This imaginary line is an extension of the Earth’s equator into space. During the equinox, the Sun’s center passes through this line, creating nearly equal day and night lengths across the globe.
For those in the Northern Hemisphere, the Sun crosses the equator from north to south during the autumnal equinox. This marks the official start of fall. Conversely, in the Southern Hemisphere, the Sun crosses from south to north, marking the beginning of spring.
Equal Day and Night? Not Exactly
While the equinox suggests that day and night are of equal length, this is not entirely accurate. In most regions, the day is slightly longer than 12 hours on the equinox. This phenomenon occurs because “sunrise” begins when the upper edge of the Sun becomes visible above the horizon, and “sunset” ends when the Sun’s upper edge disappears below the horizon. Additionally, Earth’s atmosphere refracts sunlight, bending it in such a way that the Sun appears above the horizon even when it is slightly below it.
The date when day and night are actually equal is known as Equifax. This event occurs a few days before the spring equinox and a few days after the fall equinox in both hemispheres.
Falling Temperatures: A Hallmark of Fall
As fall progresses, temperatures begin to drop. This is especially noticeable in the temperate zones, where the warm and stable weather of summer gradually gives way to cooler and more unpredictable conditions. The crisp, chilly air is a welcome change for many and a clear signal that fall is in full swing.
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Traditions and Folklore of Fall
Fall is a season rich in traditions and folklore. Across the globe, cultures celebrate the start of autumn and the fall equinox with various festivals and holidays. For example, Mabon is a pagan festival that celebrates the autumnal equinox, while Navaratri is a Hindu festival that spans nine nights in honor of the divine feminine. In some cultures, the fall equinox is also associated with the “Snake of Light,” a phenomenon observed at ancient sites like Chichen Itza in Mexico.
How Long Does Fall Last?
Fall, like all seasons, does not have a constant duration. The Earth’s elliptical orbit means that the seasons are not of equal length. On average, fall lasts for 89.8 days in the Northern Hemisphere and 92.8 days in the Southern Hemisphere. This duration is shorter than summer, which averages 93.6 days, but longer than winter, which lasts 89.0 days.
The Science Behind the Seasons
Seasons are caused by the tilt of the Earth’s axis as it orbits the Sun. The tilt of approximately 23.5 degrees causes different parts of the Earth to receive varying amounts of sunlight throughout the year, leading to the changing seasons. This tilt, combined with the Earth’s elliptical orbit, results in the differing lengths of seasons.
There are two ways to define seasons: meteorological and astronomical. Meteorological seasons are based on the annual temperature cycle and the Gregorian calendar, while astronomical seasons are based on the position of the Sun relative to the Earth.
Fall or Autumn? What’s the Difference?
Both terms “fall” and “autumn” are correct, but their usage differs depending on the region. Autumn is primarily used in British English, while fall is more commonly used in American English. Regardless of the term, both refer to the same season that precedes winter.
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Conclusion
The first day of fall, marked by the autumnal equinox, is a significant event that signals the start of a new season. As the days grow shorter and the temperatures begin to drop, nature prepares for the colder months ahead. Whether you refer to it as fall or autumn, this season is a time of vibrant colors, rich traditions, and a gradual transition from the warmth of summer to the chill of winter. So, grab your calendar, mark the date, and get ready to enjoy everything this beautiful season has to offer.
