sunrise

Sunrise is the daily event at which the upper edge of the Sun becomes visible above the eastern horizon as the Earth rotates. It marks the start of morning on most calendars and is typically contrasted with sunset, when the Sun’s upper edge sinks below the western horizon. The exact moment depends on the observer’s location, the Sun’s apparent diameter, and atmospheric refraction, which bends sunlight as it passes through the atmosphere. Because of refraction, the Sun may be visible before its geometric center fully crosses the horizon, and the center is usually about 0.8 degrees below the horizon at the moment the upper limb appears.

The timing of sunrise varies with season and latitude. It tends to shift eastward or westward along the horizon over the year, and near the equinoxes the Sun rises close to due east. At higher latitudes, the difference between sunrise times across the year is more pronounced, and extreme latitudes can experience periods without sunrise in winter or without sunset in summer.

Local conditions such as terrain, weather, and air clarity can affect the moment of sunrise. Obstructions like mountains or buildings can delay view of the Sun, while atmospheric haze can alter color and visibility. Sunrise has practical importance for daily life, navigation, and cultural traditions, and it is often associated with themes of renewal and the transition from night to day.