At the end of the year would the light hours and dark hours be roughly equal?

Answer 1

Your question:
will the sum of all day hours of a year be equal to all night hours of a year?

Answer No.

It seems simple. All small days of winter are equally compensated by all the small nights of summer. Theoretically the sum of both should be the exactly the same. But in reality it is not.

The reason is that the day starts off when you see the first edge sun over the horizon and the ends when the last edge of sun disappears below horizon. This means that in our calculations we inherently increase our day hours by as much time that the sun will take to travel 1 degree accross the sky. (The diameter of the sun as we observe it in the sky is equal to 1 degree). This amounts to extra 4 minutes of day time each day. (The sun takes 24 hours to travel 360 degrees thus it takes 24*60/360 = 4 minutes for traveling 1 degree accross the sky.)

This means that in 365 days the total day hours will be increased by about more than 60 hours than what it would be calculated if day started and ended at when the center of the sun crossed the horizon, rather than its first and last edges.

So the difference (in a 365 day year) is about 60.833 hours or 1460 minutes.

Though one can still say that considering the total daylight hours at approx 4410 hours and night hours at approx 4350, it is roughly the same. But in reality there is a different of about 61 hours.

Answer 2

There is more daylight than there is darkness.

During the course of the year the earth rotates and tilts, sometimes it's tilting towards the sun and at other times it's tilted away from the sun. Currently the northern hemisphere is tilted away from the sun so the days are shorter and the further north you go the shorter the days are.

If you were to stand anywhere on the planet and over the course of a year record how long the sun was visible in the sky (asuming there were no clouds) then it would average exactly 12 hours per day. This assumes that you start timing from the moment the *centre* of the sun is visible to the time the *centre* of the sun disappears over the horizon. If you started timing when the sun first began to appear to the moment the last part disappeared you'd get 12 hours 4 minutes per day.

However... because light bends and is reflected by our atmosphere it's already light before the sun appears over the horizon and continues to be light after the sun disappears in the evening.

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Daylight has three definitions - Civilian, Nautical and Astronomical and these correspend to the times at which the centre of the sun is 6, 12 and 18 degrees below the horizon.

Civilian is the time at which you don't need any lights on. The time between Civilian and Nautical is when it's dark enough to need lights on but no so dark you can't see. Astronomical is when it's pitch black.

It takes four minutes for the relative position of the sun to move one degree so in the morning there are 24 minutes of Civilian twilight (6 degrees x 4 minutes) before the sun comes up over the horizon and another 24 minutes in the evening. In addition there are a further 24 minutes Nautical twilight at the begining and end of the day and a further 24 minutes Astronomical twilight.

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In summary... anywhere on the planet has 12 hours of *sunlight* per day when averaged out over a whole year. 12 hours 48 minutes of *daylight* per day, 13 hours 36 minutes of daylight and twilight, and 14 hours 24 minutes when it's not pitch black.

Answer 3

Usually around the equinoxes the days and nights will be roughly equal. The exact dates when they day and night are 12 hours each are the 21st March and 21st September. So say for 3 weeks either side of these dates the hours of light and darkness would be more or less equal.

Answer 4

I think everyone has misunderstood your question.

If I understand correctly, I think you're asking, if we added up all the hours of daylight and all the hours of night, for a whole 365.25 days of a year, would they be equal?

Right?

If that's your question, then I think the short answer is no. There would be more day than night.

Why? Because, even on the days of the Equinox - which are halfway between the longest and shortest days - the sun is still visible for slightly longer than 12 hours, due to the curvature of the Earth.

Also, we wouldn't generally say night has started as soon as the Sun disappears. It is still light, and therefore daytime, for quite a while after sunset.

So, I think the light hours would win by a significant margin.

Answer 5

At the end of the year would the light hours and dark hours be roughly equal?

If we are talking about the sky being bright ragardless?
No.
Like Amancalledchuda said, the sun lights the sky even before and after rising and setting.

If we are talking about direct sunlight on the ground?
Yes, roughly, but not quite..

Because you have to account for everywhere on the planet. Not just one hemisphere, and not just one place.

Its just a matter of common sense.

Because the sun is larger than the earth, there is slightly more earth in sunlight than there is in shade at any one time.
But only just. It would be more significant were the earth closer to the sun, but because of the distance the difference is negligable.

It would be like saying
Sunlight 50.001% of the time.
Dark 49.999 % of the time instead of just saying 50/50.

Answer 6

Light and dark are of equal length (theoretically) at the the equinox not near a solstice - ie. Spring and Autumn, not summer or winter!

Answer 7

Day and night are the same length at the Equinoxs, March 21 and Sept 21.

Answer 8

Equin - Equal
Nox - Night (latin)
Happens around march 20 and september 23 every year

Wikipedia will give you more information

Answer 9

hello, No, i for my area do no longer believe in international Warming, and that i doubt turning off some lights, is going to maintain our planet. yet who's well-known with? i might desire to be incorrect. in my view ''international Warming'' is a scam to tear funds off tax payers, Earth is purely dealing with a cycle.

Answer 10

This would very in each area of the country