The first day of spring was Sunday, March 20, 2023, at 5:24 a.m. EDT. For those of us in the Northern Hemisphere, this was marked by the arrival of the Vernal Equinox (otherwise known as the “First Point of Aries“).
Traditionally, we celebrate the first day of spring on March 21, but astronomers and calendar manufacturers alike now say that the spring season starts on March 20th, in all time zones in North America. In 2020, spring fell on March 19th, the earliest first day of spring in 124 years!
Regardless of what the weather is doing outside, spring equinox marks the official start of the spring season. Get our official spring forecast.
What Does Vernal Equinox Mean?
Vernal translates to “new” and “fresh,” and equinox derived from the Latin aequus (equal) and nox (night).
So what does that mean? Essentially, our hours of daylight—the period of time each day between sunrise and sunset—have been growing slightly longer each day since the winter solstice in December, which is the shortest day of the year (at least in terms of light).
Even though we know that after December 21st, the days start getting steadily longer, we still see more darkness than light over the course of a day in those three months leading up to spring. The vernal equinox marks the turning point when daylight begins to win out over darkness.
At this moment, the direct rays of the Sun are shining down on the equator producing the effect of equal day and night (give or take a few minutes, see below). After the vernal equinox, the direct rays of the Sun migrate north of the Equator (with hours of daylight steadily growing longer) until they finally arrive at the Tropic of the Cancer (latitude 23.5 degrees north).
The migration of the Sun’s direct rays comes to a halt on that day; this is as far north as they will go. We call this the summer solstice (solstice is a suspension of the migration of the Sun’s direct rays). It is the longest day of the year in terms of hours of daylight.
After the summer solstice, the direct rays proceed to head south and the days begin to grow shorter. It will take another three months, until the autumnal equinox for the periods of daylight and darkness to reach equilibrium once again.
The rays ultimately reach the Tropic of Capricorn (latitude 23.5 degrees south) on the day of the winter solstice and the whole cycle begins again!
Length of Day Vs. Night
A question revolving around the vernal equinox concerns the length of day versus night. We have been taught that on the first days of spring and autumn, the day and night are equal to exactly 12 hours all over the world.
Yet, if you check the calendar pages in our Almanac, you will find that this is not so. In fact, our tables tell you that on the days of the spring and fall equinox, the length of daylight is actually longer than darkness by several minutes.
The reason this happens can be attributed to our atmosphere. If Earth was a planet that did not have an atmosphere, then yes, on the equinox days the length of the day and night would be exactly even.
However, our atmosphere acts like a lens and refracts (bends) its light above the edge of the horizon. Put in another way, when you watch the Sun either coming up above the horizon at sunrise, or going down below the horizon at sunset, you are looking at an illusion — the Sun is not really there, but already below the horizon.
As a result, we actually end up seeing the Sun for a few minutes before its disc actually rises and for a few minutes after it has actually set. Thus, thanks to atmospheric refraction, the length of daylight on any given day is increased by approximately six or seven minutes.
Why Does the First Day of Spring Change?
There are a few reasons why seasonal dates can vary from year to year. The first is…
- A year is not an even number of days and neither are the seasons.
- Earth’s elliptical orbit is changing its orientation (skew), which causes the its axis to constantly point in a different direction, called precession.
Since the seasons are defined as beginning at strict 90-degree intervals, these positional changes affect the time the earth reaches each 90-degree location in its orbit around the sun.
Second, the pull of gravity from the other planets also affects the location of Earth in its orbit.
Is Spring Getting Shorter?
The current seasonal lengths for the Northern Hemisphere are (approximately):
- Summer — 93.641 days
- Autumn — 89.834 days
- Winter — 88.994 days
- Spring — 92.771 days
As you can see, the warm seasons, spring and summer, combined are 7.584 days longer than the colder seasons, fall and winter (good news for warm weather admirers!).
However, spring is currently being reduced by approximately one minute per year and winter by about one-half a minute per year. Summer is gaining the minute lost from spring, and autumn is gaining the half a minute lost from winter.
Winter is the shortest astronomical season, and with its seasonal duration continuing to decrease, it is expected to attain its minimum value — 88.71 days — by about the year 3500.
Why The Changes?
So why, you might ask, are the “warm seasons” (spring and summer), longer than
the “cold seasons” (autumn and winter)?
It goes back to Earth’s elliptical orbit again, as mentioned above. We are 3.1 million miles closer to the Sun (called perihelion) in early January, as compared to early July, when we are farthest (called aphelion). And the closer a celestial body is to the Sun, the faster it must move in its orbit—gravity insists upon that, that’s a fundamental, natural law that was demonstrated 400 years ago by the astronomer, Johann Kepler. That means during cold months, when we are closest to the Sun, we are sweeping fastest through our orbit in space. In July, when we’re farther from the Sun, we’re moving more slowly.
In the Northern Hemisphere, the astronomical Start of Spring is also known as the Spring equinox, and in 2021 it happens on March 20, at 5:37 a.m. EDT.
This year, Spring will last from March 20 until June 20, when Summer officially starts.
What is the Spring Equinox?
The Spring Equinox, which is also called the Vernal or March Equinox, happens when the Sun heads north and crosses the equator line. When this happens, the Northern Hemisphere of the Earth starts to tilt more towards the Sun, which results in longer and warmer days.
So, the Spring Equinox signals the arrival of Spring in the United States, and with it the nicer weather, and the blooming of flowers and plants. In the Southern Hemisphere, the Vernal Equinox signals the start of Autumn, as this hemisphere becomes tilted away from the Sun.
During the equinox, the day and night are nearly the same lengths, approximately 12 hours long each. It is at this point that the change happens when the days become longer and the nights become shorter.
The end of Spring is signalled by the Summer Solstice, which happens in June, and marks the arrival of Summer in the Northern Hemisphere.
Characteristics of Spring
It is during Spring that the temperature starts getting warmer, after months of cold and snow. Spring is also one of the wetter seasons. This is the reason why during Spring the snow begins to melt, and trees and flowering plants start blossoming again.
One of the most identifying characteristics of Spring is its colors. Because plants and flowers start to bloom, the world becomes green and colorful again, after being bare and grey for so long during Winter.
This season is also often connected with rebirth and regrowth. Farmers sow their seeds ready for harvest in the Summer, and animals awaken from their hibernation periods and others have their babies.
However, Spring in the United States is not all flowers and sunshine. It is also during this season that tornadoes become more frequent in the Tornado Alley area. With Spring, there are also more thunderstorms and hail storms.
Important Dates associated with Spring
Spring has always had a big significance when it comes to dates and celebrations. In ancient times, it was during Spring that many pagan rituals and ceremonies took place, mainly weddings and other fertility-related rites. These traditions have, in one way or another, been passed on through to modern times, and today some of the most important dates we celebrate take place during Spring:
- Mardi Gras and Carnival - In some cultures this is the festival of the new year.
- Easter - The most important feast day in Christianity, celebrating the resurrection of Jesus Christ.
- Passover - Where Jewish people celebrate their escape from slavery.
The Start of Spring dates from 2021 to 2024
- 2021 Saturday, March 20, at 5:37 A.M. EDT
- 2022 Sunday, March 20, at 11:33 A.M. EDT
- 2023 Monday, March 20, at 5:24 P.M. EDT
- 2024 Tuesday, March 19, at 11:06 P.M. EDT
Other Articles that will interest you
-
Start of Summer
-
Seasons of the Year in the United States
-
Start of Fall