The phenomenon of early sunrise is caused by atmospheric refraction, where the Sun appears to rise earlier than its actual geometric position.
Here's a breakdown:
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Atmospheric Refraction: As sunlight enters the Earth's atmosphere, it bends or refracts. This bending occurs because the atmosphere's density increases as you get closer to the Earth's surface.
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How it Works: The Sun's rays, before they actually clear the horizon, are bent downwards towards the observer. This makes the Sun appear to be higher in the sky than it actually is.
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Result: Consequently, we see the Sun before it has physically risen above the horizon, resulting in an "early sunrise." The same effect causes a delayed sunset, as we continue to see the Sun after it has physically dipped below the horizon.
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Magnitude: This effect advances sunrise by approximately 2 minutes and delays sunset by about 2 minutes, for a total of about 4 minutes of extra daylight per day.
In short, the atmosphere acts like a lens, bending the light from the Sun and making it appear above the horizon before it actually is.
