Why does atmospheric refraction cause longer days and shorte nights?
Refraction bends sunlightlight as it passes through the atmosphere, causing the Sun to *always* appear higher in the sky than it actually is. Consequently, the Sun appears to be above the horizon before it actually rises in the morning, and also appears to still be above the horizon when it has actually already set in the evening. This makes the daylight portion of the day a few minutes longer than it would be if the atmosphere was absent. Atmospheric refraction is a very different process than scattering (described in the first answer to your question) which is what makes the sky blue during the day and the entire sky stay bright after the sun has set. The Earth’s tilt on its rotational axis does cause the seasons and varying length of the day, but this has nothing to do with refraction.
