Does every location on Earth have the same amount of daylight hours (not sunshine) in a YEAR?

Question

i.e. Anchorage/Rio de Janeiro, New York/Singapore, Stockholm/Sydney..and so on?

Answer 1

This is a question that I've pondered too. I believe all the answers given so far are incorrect. For one thing, every answer so far has neglected that the Earth has an atmosphere! Because of the atmosphere, daylight is a bit longer than it would be otherwise, because atmospheric refraction allows us to see the sun when it is geometrically below the horizon. That is one reason why daylight is longer than 12 hours at the equinoxes. I think this favors longer daylight at high latitudes, because in general the sun spends more time close to the horizon at those high latitudes. It actually wouldn't be THAT hard to calculate this for a few locations and find the correct answer that way. I don't have the time to do that right now, but for someone that does, you can find the information you need on the US Naval Observatory website http://www.usno.navy.mil/

Here is a quote from their FAQ which may be instructive:

"For computational purposes, sunrise or sunset is defined to occur when the geometric zenith distance of center of the Sun is 90.8333 degrees. That is, the center of the Sun is geometrically 50 arcminutes below a horizontal plane. For an observer at sea level with a level, unobstructed horizon, under average atmospheric conditions, the upper limb of the Sun will then appear to be tangent to the horizon. The 50-arcminute geometric depression of the Sun's center used for the computations is obtained by adding the average apparent radius of the Sun (16 arcminutes) to the average amount of atmospheric refraction at the horizon (34 arcminutes)."

Anyway, unless somebody can find something more definitive I think a calculation is the best way to go (just huffing and puffing and saying you're right doesn't really cut it).

To add just a little bit more, I did a spot check on the time between sunrise and sunset at the equinoxes for a high latitude site (82N) and found that daylight was more like 12.5 hours whereas at the equator it was 12.2 or so. This leads me to believe the my initial guess is correct, that high latitudes have more daylight. Still the best way to check is to actually calculate it.

Answer 2

I'd have to figure it out, but I'd have to say yes. Here's why: Cities along the equator basically get 12 hours of daylight every day, and the poles get sunlight 24 hours a day for 6 months but then they get 24 hours of darkness. If you do the math, 6 months of daylight 24 hours a day is the same as 12 hours of daylight year-round. I know there are major fluctuations between the equator and the poles, but if you look carefully you'll see that the more light a location gets during the summer (above and beyond 12 hours a day) the less light that location gets during the winter. Interesting question...I don't have evidence to back it up but I still believe every location on Earth has the same amount of daylight hours over the course of a year.

Answer 3

Good question!

Answer: No, they do not, because the Earth is in an elliptical orbit around the Sun.

It seems as if they should, because you might think that logically for every winter day, there is a summer day, etc.

But this is not correct. Because the Earth is in an elliptical orbit, which is closest to the Sun on January 4, we are moving faster through the orbit and spend less time in northern winter than in northern summer. Thus here in the northern hemisphere, fall and winter (181 days) are shorter than spring and summer (184 days). We therefore (in the north) have more days of longer-day-than-night than shorter-day-than-night. So over the course of a year, the Northern hemisphere gets more than 50% daytime.

The opposite is true for the southern hemisphere, which gets slightly less than 50% daytime.

If the Earth's orbit were circular, time spent in fall-winter would equal spring-summer and yearly accumulated daytime would be 50% everywhere.

Answer 4

Amount Of Daylight

Answer 5

In the tropics, where the Earth's surface is nearly perpendicular to the Sun's rays, each square metre gets more heat and light in the course of a year than near the poles, where the surface is at an oblique angle. This is why it's colder at the poles. It's the flow of heat from the tropics to the poles that drives the world's weather systems, just like the hot combustion chambers and cool exhaust drive a car engine.

Answer 6

My original answer was no because I know the equator gets sun all year round, whereas the poles have the 6 months darkness/6 m onths light. But if it's true that the equator gets 12 hours a day all year round, then yes. But I'm still leaning towards no because the sun is not always on the equator. On the equinoxes it comes up to the Tropic of Cancer and the Tropic of Capricorn.

My vote ... no.

Answer 7

Yes. This is averaged out differently during the year for any given location, however. The equator has much less variation through the year, and gets its sunlight for about half a day, every day, throughout the year, and so has about twelve hours of daylight every day, no matter what the season. Since our axis is tilted, the northern hemisphere gets more sunlight (longer days) during one half of the year, and the southern hemisphere gets more during the other half, but it still balances out to being about the same total hours.

The north pole has no night during the summer months, while the south pole is in total darkness but it all averages out in the end.

To add to another answer about the elliptical orbit - yes, our earth's orbit is elliptical, but the shape (or eccentricity) of the earth's orbit changes on a 413,000-year cycle, going from more circular to more like an oval. In other words, the effect of the elliptical orbit is averaged out over time.

Answer 8

With its bright sandy beaches, leaping mountains and picturesque harbour, it's no wonder that Rio de Janeiro is called the "cidade maravilhosa", or marvellous town and with hotelbye you are able to get the possibility and visit this unique city. Rio de Janeiro is facing the South Atlantic shore and could be the second-largest city in Brazil. That town is blessed with one of the most lovely natural settings for a area in the world. The stunning landscape is one of the causes that visitors decided Rio de Janeiro. During carnival period, a festival that every one noticed, the roads fill with audio and ornately costumed dancers getting tourists from all over the globe.

Answer 9

location earth amount daylight hours sunshine year

Answer 10

Yes. Every location on Earth nets at the end of a year 1/2 year of daylight.

The hours of daylight a location receives throughout the year is modelled by a sine function, which, being an odd function(symmetric with respect to the origin), indicates that the number of hours above the axis equals the number of hours below it. This can only occur when the hours are equal, hence, every location on Earth receives 1/2 year each of day and night.

..and to whoever gave me a thumbs down, go back to school, this answer is correct, unless you factor in Earth's slightly-elliptical orbit, which will shift the difference by a few minutes per year, particularly at higher latitudes. Other than that, it is equal day and night everywhere over the year.

BTW, this is not an opinion poll folks, this is a mathematical problem with a single mathematical solution. The number of hours of daylight a location receives each year has nothing to do with popular opinion, so please don't post unless you have something other than a guess, eh?