Now Playing
Y100 FM

Posted: March 20, 2018

Spring 2018: 5 things to know about the vernal equinox

Meteorological Spring and Astronomical Spring – What’s the Difference?

By Austin American-Statesman

Spring is finally here with the arrival of the vernal equinox, as determined by people who base their seasons on the Earth’s position relative to the sun and stars. Here are five things to know:

1. What is it? During the vernal equinox, the sun shines directly on the equator, and the northern and southern hemispheres get exactly the same amount of rays. Night and day are almost equal length.

>> Spring 2018: What’s the difference between meteorological spring and astronomical spring?

2. What does equinox mean? The Earth spins on a tilted axis, which means its northern and southern hemispheres trade places in receiving more light as it orbits the sun. The axis is not inclined toward or away from the sun at the equinox, which is derived from the Latin words for equal (aequus) and night (nox).

3. Why is it important? For ancient societies, the vernal and autumnal equinoxes marked when winter turned to spring and when summer turned to fall, respectively, and helped people track time-sensitive things, such as when to plant crops.

>> Read more trending news 

4. Didn’t spring start already? Meteorological spring started March 1. Forecasters like to start the season on the first day of March because they prefer a calendar in which each season starts on the same day every year. It helps with record keeping, among other reasons. But the Earth, sun and stars don’t quite conform to the Gregorian calendar – thus the vernal equinox doesn’t fall on the same day every year.

5. What's next? The summer solstice is June 21, but meteorological summer begins a few weeks earlier on June 1.

– The Cox Media Group National Content Desk contributed to this report.


Related

ccompton@ajc.com/ccompton@ajc.com

Spring 2018: 5 things to know about the vernal equinox

ccompton@ajc.com/ccompton@ajc.com

Spring 2018: 5 things to know about the vernal equinox

040715 AUGUSTA: A patron checks out a Dogwood tree beside the second fairway during the Masters at Augusta National Golf Club on Tuesday, April 7, 2015, in Augusta, Georgia. Curtis Compton / The Atlanta Journal-Constitution

Spring 2018: What’s the difference between meteorological spring and astronomical spring?

Thursday, March 1, marked the first day of meteorological spring. Astronomical spring, on the other hand, won’t begin for another few weeks.

Confused? You’re not alone.

Here are some things to know about the two seasons:

What’s the difference?

According to the National Oceanic and Atmospheric Administration, meteorologists follow the meteorological seasons based on the annual temperature cycle, whereas climatologists follow astronomical seasons, which are defined by the Earth’s position in relation to the sun.

» RELATED: When is Easter 2018 and why does the date change each year?

What are solstices and equinoxes?

Astronomical seasons are defined with two solstices and two equinoxes.

According to the National Weather Service, the summer solstice occurs the moment the earth’s tilt toward the sun is at a maximum and when the sun is directly over the Tropic of Cancer. The sun is at its highest point in the sky anywhere north of the Tropic of Cancer. This is the longest day of the year in those areas.

The winter solstice occurs when the sun is directly over the Tropic of Capricorn and marks the shortest day and longest night of the year.

Equinoxes, on the other hand, are times of the year when the earth’s axis is tilted neither toward nor away from the sun. On these days, there’s almost an equal amount of daylight and darkness at all latitudes. But days are a little longer at the higher latitudes.

» RELATED: It’s Lenten season: Why it’s not always good to give up things for Lent

Approximately when do the solstices and equinoxes occur in the northern hemisphere?

Summer solstice: June 21

Winter solstice: Dec. 22

Vernal/spring equinox: March 21

Autumnal equinox: Sept. 22

When does astronomical spring begin?

Astronomical spring begins on the vernal or spring equinox, around March 21. 

» RELATED: Sip & Swine BBQ Festival: 16 things to do this weekend in Atlanta

Which do we typically use to define seasons?

While people have long used the sun’s alignment and other natural phenomena to mark time, meteorological seasons are more closely tied to our calendar than the astronomical seasons. For example, meteorological spring includes March, April and May. Summer includes June, July and August. Fall includes September, October and November. And lastly, winter includes December, January and February.

Meteorological seasons are also more consistent compared to astronomical seasons.

Why do we typically use meteorological seasons for our civil calendars?

The exact dates of the solstices and equinoxes can vary between 89-93 days due to the earth’s elliptical orbit and whether or not it’s a Leap Year.

Due to the consistency of meteorological seasons (each season is roughly 90-92 days long), calculating seasonal statistics from monthly numbers is much easier. According to NOAA, this data is often used to understand trends in agriculture, commerce and more.

Learn more about the seasons at ncei.noaa.gov.

 
 

 

@Y100SanAntonio Instagram

 

Amazon Alexa

Enable our Skill today to listen live at home on your Alexa Devices!