Sunrises

Sunrise is the daily moment when the upper edge of the Sun becomes visible above the horizon, marking the beginning of daytime in most places. It results from the rotation of the Earth toward the east, making the Sun appear to rise in the east and follow a arc-shaped path across the sky.

The exact moment of sunrise is defined as when the upper limb of the Sun first appears above the horizon. Atmospheric refraction lifts the Sun’s image as it nears the horizon, and the Sun’s apparent diameter is about 0.5 degrees. Consequently, the Sun’s center is typically about 0.8 degrees below the horizon at first contact, with the interval to full sunrise lasting a few minutes depending on location and conditions.

Sunrise timing and direction vary with latitude, season, and local horizon. The Sun rises roughly in the east, but its azimuth shifts northward in spring and southward in autumn due to the tilt of the Earth's axis (about 23.5 degrees). Elevation of the observer and geographical features such as mountains or coastlines can also alter the apparent time of sunrise.

Atmospheric conditions influence sunrises. As sunlight travels through a thicker layer of atmosphere at dawn, shorter blue wavelengths scatter out, leaving longer red and orange tones. This can produce vivid colors, especially when the air contains dust or pollutants. The time and hues of sunrise are of interest in meteorology, navigation, and culture, and are commonly celebrated in photography and literature.