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When are day and night the same length? |
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In theory, day and night should be of equal length during the vernal equinox and the autumnal equinox when the Sun rises in the east and sets in the west. This occurs all over the world at the same time.
But, in practice, we don’t sense day and night being of equal length on both occasions but a couple of days earlier. Why’s that?
Well, the atmosphere around the Earth affects the sunlight near the horizon so that it looks as though the Sun is higher in the sky that it really is.
That’s why we see the solar disc a couple of minutes before it rises in the morning and a couple of minutes after it has actually disappeared below the horizon in the evening.
We could say that the atmosphere takes a little from the night and gives it to the day.
Dela |
