Why Mornings Stay Dark After the Winter Solstice
Today is 21st December, the Winter Solstice, the shortest day of the year. While we often think of this day as the turning point when the nights begin to pull out and the days get longer, there’s a curious twist: the mornings actually get darker before they start to brighten. For those of us watching the sunrise, it’s not until early January that we finally notice the mornings becoming lighter. Why does this happen?
This seasonal quirk is more than just a fun fact. It’s a glimpse into the elegant dance between Earth, the Sun, and the cosmos, governed by the interplay of our planet’s orbit and axial tilt.
The Science Behind the Phenomenon
1. Earth’s Elliptical Orbit
Earth’s path around the Sun isn’t a perfect circle—it’s an ellipse. This means Earth moves faster in its orbit when it’s closer to the Sun (perihelion, around early January) and slower when it’s farther away (aphelion, around early July). As a result, the Sun’s apparent motion across the sky isn’t uniform throughout the year. This variation shifts solar time, affecting the timing of sunrise and sunset.
2. Axial Tilt
Earth’s axis is tilted at about 23.5 degrees. This tilt creates our seasons and affects the distribution of daylight across the year. Around the Winter Solstice, the Sun is at its lowest point in the sky in the Northern Hemisphere, leading to the shortest day.
3. The Equation of Time
The combination of Earth’s elliptical orbit and axial tilt leads to variations in solar time, known as the equation of time. This is why the shortest day doesn’t perfectly align with the earliest sunset or latest sunrise.
When Does the Morning Start to Brighten?
Here in Lowestoft, the UK’s most easterly point, we can see this effect clearly. On 21st December, the sun rises at 08:02 and sets at 15:41. While sunsets begin to grow later almost immediately after the solstice, sunrise times continue to shift later:
- 22nd December: Sunrise 08:02, Sunset 15:42
- 27th December: Sunrise 08:04, Sunset 15:46
- 3rd January: Sunrise 08:04, Sunset 15:52
- 4th January: Sunrise 08:03, Sunset 15:53
- 7th January: Sunrise 08:02, Sunset 15:57
By early January, the shifting solar time balances out, and the mornings finally begin to lighten. This is due to the slight lengthening of the solar day (the time between solar noons), which temporarily delays sunrise even as the days grow longer overall.
The Role of the Analemma
If you’ve ever seen a figure-eight shape on a globe or a sundial, that’s the analemma. It’s a visual representation of the Sun’s position in the sky at the same time every day throughout the year. This shape is influenced by both Earth’s tilt and elliptical orbit and helps explain the variations in sunrise and sunset times.
A Seasonal Perspective
The delayed brightening of mornings after the Winter Solstice is a subtle but beautiful reminder of the complexity of our planet’s motion. It shows us that change often unfolds gradually, even when the turning point has already passed. As we celebrate the return of longer days, let’s take a moment to appreciate the celestial mechanics that guide our planet’s journey around the Sun.
Did You Know?
- The earliest sunset occurs before the Winter Solstice (around 12th December in the UK).
- The latest sunrise happens after the solstice (early January).
- Earth reaches perihelion, its closest point to the Sun, in early January.
Closing Thoughts
As the mornings begin to brighten in the new year, they bring a sense of hope and renewal. The gradual return of the light reminds us to embrace patience and trust the process of transformation. Just as the Sun’s rhythm shapes our seasons, our own lives unfold in cycles of growth and renewal. Here’s to finding warmth and light during this magical time of year.