Greenland, the world’s largest island, is often misunderstood regarding its daylight patterns. It experiences extreme variations in daylight, not perpetual light or darkness. Instead, Greenland is characterized by periods of continuous sunlight and prolonged darkness. This interplay of light and shadow ties directly to Earth’s tilt and Greenland’s high-latitude location.
The Midnight Sun Phenomenon
During the summer months, regions north of the Arctic Circle experience the “Midnight Sun,” where the sun remains visible at midnight. This occurs because the sun never fully dips below the horizon. Its duration varies significantly with latitude. For instance, in the northernmost town of Qaanaaq, the sun remains above the horizon for approximately three and a half months, from late April to late August.
Further south, towns like Ilulissat (still above the Arctic Circle) experience the Midnight Sun from early June to mid-July. Even south of the Arctic Circle, locations like Nanortalik, though not experiencing the full Midnight Sun, still enjoy bright nights with up to 20 hours of daylight. This extended daylight transforms the landscape, bathing icebergs and fjords in warm, vibrant hues of pink, purple, yellow, and red.
The Science Behind the Light
The occurrence of the Midnight Sun is due to Earth’s axial tilt, which is approximately 23.5 degrees relative to its orbital plane. As Earth orbits, this tilt means that during the Northern Hemisphere’s summer, the North Pole is angled towards the sun. Consequently, areas within the Arctic Circle receive continuous sunlight for days or even months.
The Arctic Circle is an imaginary line of latitude at about 66°34′ North. It marks the southernmost point in the Northern Hemisphere where, on the summer solstice, the sun does not set for at least 24 hours. Due to atmospheric refraction, the Midnight Sun can sometimes be observed slightly south of this geographical boundary. The tilt of Earth’s axis, not its distance from the sun, is the main reason for these seasonal light variations.
The Counterpart: Polar Night
In contrast to summer’s continuous daylight, winter in Greenland’s Arctic regions features the “Polar Night,” when the sun does not rise above the horizon for 24 hours or more. This phenomenon, opposite to the Midnight Sun, occurs when the North Pole is tilted away from the sun. The duration of the Polar Night also depends on the latitude, being most pronounced in the northernmost settlements.
In Qaanaaq, the Polar Night can last for nearly four months, from late October to mid-February. However, Polar Night does not mean absolute darkness throughout this entire period. Instead, many areas experience a prolonged twilight, where the sky offers some natural light from the moon, stars, and the glow of the Northern Lights reflecting off the snow.
Life Under Extreme Light and Dark
The light cycles in Greenland influence both human and animal life. For humans, the prolonged daylight of summer can alter sleep patterns, with some residents adapting their daily routines to the constant brightness. Conversely, the extended darkness of winter prompts changes in activity, often leading to more indoor community gatherings. While communities adapt, some studies have explored the potential for light-related imbalances to affect human well-being, especially sleep and mood.
Wildlife in Greenland has developed adaptations to these conditions. Reindeer, for example, have eyes that can perceive ultraviolet light, which helps them forage and identify predators in the light conditions of the Arctic. Other animals like polar bears and muskoxen possess thick fur and efficient physiological systems to endure the cold and periods of scarce food, often linked to ice conditions and snow cover. These adaptations allow life to persist and thrive in an environment defined by its shifts between unending day and prolonged night.