The term "sunrise time" typically refers to the moment when the upper edge of the Sun's disk becomes visible above the horizon. It marks the beginning of the day and is often considered the starting point for measuring time and daylight hours.
At sunrise, the sky is usually still relatively dark, especially before dawn. However, as the Sun rises above the horizon, it gradually illuminates the atmosphere, leading to the gradual increase in light. So, the actual moment of sunrise is when the Sun's disk becomes visible, and it may take a little time for the surroundings to brighten up significantly.
The amount of time it takes for the sky to transition from darkness to full daylight can vary depending on various factors such as the time of year, location, and weather conditions. Atmospheric conditions, clouds, and other factors can influence how quickly the sky brightens after sunrise.
It's worth noting that the term "sunrise time" can also be used more broadly to refer to the period leading up to and immediately following the moment when the Sun is visible above the horizon. During this time, the sky gradually transitions from darkness to increasing light as the Sun rises higher.