The Omega Sun phenomenon is a rare and captivating optical effect that occurs during sunset or sunrise, where the sun appears to take on the shape of the Greek letter Omega (Ω). This distinctive appearance is created when atmospheric refraction causes the bottom portion of the sun to appear detached from the main solar disk, connected by vertical columns of light on either side.

This phenomenon typically occurs when the sun is very close to the horizon and specific atmospheric conditions are present. The effect requires a strong temperature inversion layer near the surface, which bends light rays at different angles depending on their height above the horizon. The result is a mirage effect that distorts the sun's circular shape into the characteristic Omega form.

The Omega Sun is most commonly observed over water or flat terrain where temperature inversions are more likely to form. Observers in coastal areas, on ships at sea, or in polar regions have the best opportunities to witness this spectacular display. The phenomenon typically lasts only a few seconds to a couple of minutes as the sun continues its journey below the horizon.

Understanding the Omega Sun requires knowledge of atmospheric optics, particularly how light behaves when passing through layers of air with different temperatures and densities. The phenomenon represents one of nature's most beautiful demonstrations of the physics of light refraction and atmospheric science.

The green flash is a brief optical phenomenon that appears as a green spot or ray of light visible just above the sun immediately after sunset or before sunrise. This fleeting display typically lasts only one or two seconds and is considered one of the holy grails of atmospheric optical observations. Despite its rarity, the green flash is a real physical phenomenon caused by the refraction of sunlight in the atmosphere.

When sunlight passes through the Earth's atmosphere, it is refracted, or bent, with shorter wavelengths (blue and green) being refracted more than longer wavelengths (red and orange). Normally, blue light would create a blue flash, but it is scattered away by the atmosphere, leaving green as the most visible short wavelength color. At the moment the sun dips below or rises above the horizon, the atmospheric refraction separates the colors slightly, and if conditions are right, the green wavelength becomes briefly visible.

Observing a green flash requires a clear, unobstructed view of the horizon with minimal atmospheric turbulence. Ocean horizons provide ideal viewing conditions because of their flatness and the clean air above water. The phenomenon can also appear in different forms, including the inferior-mirage flash, mock-mirage flash, and sub-duct flash, each created by different atmospheric conditions and temperature profiles.

The green flash has captured human imagination for centuries and has been referenced in literature, folklore, and maritime traditions. Some legends claim that those who witness a green flash will never go wrong in matters of the heart, while sailors have long considered it a sign of good fortune. Scientifically documenting and photographing green flashes has become a pursuit for dedicated atmospheric optics enthusiasts around the world.

Beyond the Omega Sun and green flash, numerous other optical phenomena can occur at sunrise and sunset. The mock mirage, also known as the Fata Morgana when complex, creates distorted images of distant objects through layers of air with different temperatures. These mirages can make the sun appear stretched, compressed, or segmented into multiple parts, creating surreal shapes as it approaches the horizon.

Crepuscular rays, commonly called "sun rays" or "god rays," are shafts of sunlight that appear to radiate from the sun's position. These dramatic beams occur when clouds, mountains, or other obstacles partially block the sun, casting shadows through dust, moisture, or haze in the atmosphere. Though the rays are actually parallel, perspective makes them appear to diverge from a single point near the horizon.

The Belt of Venus is a pink or reddish band that appears in the sky opposite the setting sun, accompanied by the Earth's shadow, a dark blue-grey band below it. This atmospheric phenomenon is caused by the scattering of red sunlight in the atmosphere during twilight. The effect is named after the planet Venus, though it has no actual connection to the planet, and can be observed from any location with a clear view of the horizon opposite the sunset.

Additional phenomena include the blue flash (rarer than green), red flash, sunset pillars, and various forms of atmospheric distortion that can make celestial bodies appear flattened, elongated, or fragmented. Each of these effects provides insight into the complex interactions between light and the Earth's atmosphere, demonstrating the beautiful physics that occurs during the transitional periods between day and night.

The Omega Sun Project is dedicated to documenting, studying, and educating people about the Omega Sun phenomenon and related atmospheric optical effects that occur at sunrise and sunset. Founded by enthusiasts and researchers passionate about atmospheric optics, the project serves as a comprehensive resource for anyone interested in these remarkable natural displays.

Our mission is to collect photographic evidence, eyewitness accounts, and scientific data about the Omega Sun and associated phenomena from observers around the world. By creating a centralized database of observations, we aim to better understand the atmospheric conditions that produce these effects, identify the best locations and times for observation, and develop predictive models that can help future observers plan their viewing opportunities.

The project brings together amateur photographers, professional scientists, meteorologists, and curious individuals who share a fascination with the beauty and physics of atmospheric optics. We provide educational resources, observing guides, and simulation tools to help people understand and appreciate these phenomena. Through our gallery and community contributions, we showcase the stunning diversity of solar optical effects captured by observers from coastal shores to polar regions.

Whether you're a seasoned atmospheric optics photographer or someone who has just discovered the wonder of these phenomena, the Omega Sun Project welcomes your participation. Share your observations, learn about the science behind what you see, connect with other enthusiasts, and help advance our understanding of these fleeting moments when physics and nature combine to create unforgettable visual spectacles at the horizon.