Night

The nights are shorter than the days on average due to two factors. One, the sun is not a point but has an apparent size of about 32 arc minutes. Two, the atmosphere refracts sunlight so that some of it reaches the ground when the sun is below the horizon for about 34 minutes of arc. The combination of these two factors means that light reaches the ground with the center of the sun is below the horizon for about 50 minutes of arc.Without these effects, day and night would be the same length in the fall (autumn / fall) and vernal equinox (spring), the moments when the sun passes over Ecuador. In fact, around the equinoxes the day is almost 14 minutes longer than the night in Ecuador, and even more towards the poles. The summer and winter solstices mark the shortest and the longest night, respectively. The closer a place or the North Pole or the South Pole, the larger the range of variation in the length of the night. Despite the equinoxes occur at a nearly day and night for the same length before and after an equinox the ratio of day to day changes more rapidly in high latitudes than in low latitude. In the Northern Hemisphere, Denmark has shorter nights in June than India has. In the Southern Hemisphere, Antarctica has more nights in June that Chile has. The northern and southern hemispheres of the world experience the same patterns of night life at the same latitude, but the cycles are 6 months apart so that one hemisphere experiences long nights (winter), while the other is experiencing short nights (summer).Between the pole and the polar circle, the variation in daylight hours is so extreme that part of the summer, and there is no intervening night between consecutive days in winter is a period no intervening day between consecutive nights.