What does the length of day have to do with seasons?
95409
When we're on equinoxes, ie, mid spring and mid fall, the sun is travelling on a path where its altitude at noon = your lattitude. \n\nSo lets take Montreal for example, at almost a 45 degree lattitude. Imagine a line drawn across the sky so that the highest point the sun is at is 45 degrees.\n\nLets move to summer. The angle the sun will be at, during noon on the longest day (the solstice) will be 45 + 23.5 degrees (the tilt of the earth) = 68.5 degrees.\n\nNow during winter, the sun will only climb to 45 - 23.5 = 21.5 degrees.\n\nif you've drawn these lines, you'll notice that the winter line is extremely shorter than the summer line - the amount of time the sun is above the horizon is shorter because you've dropped the arc line significantly, covering up more of the sun's path.\n\nI hope I've conveyed this adequately - the only way to properly see this is to picture it.
717718
In the time it takes the Earth to make one turn on its axis relative to the stars, it also moves relative to the Sun. So a day later, the Sun is not in the same spot relative to the stars and the Earth has to rotate for about another 4 minutes to put the Sun back in the same apparent position.  \n\nThe actual length of a Solar days varies during the year, because the Earth's orbit is elliptical, and the orbital speed varies slightly. If you rely on a sundial to tell time, it will run fast and slow by about 15 minutes in the course of a year. Our 24-hour standard day is the average of the variations, and so is called a Mean Solar Day.\n\nThe sidereal day, on the other hand, is precise to a minute fraction of a second - the Earth does wobble a little and is very gradually slowing down besides, so it's not perfectly repeatable.
75399
The reason there is differing amounts of daylight is that the Earth's axis is tilted with respect to the plane of its rotation about the sun. When the north pole is tilted towards the sun, the northern hemisphere days get longer. The point in the Earth's orbit about the sun where the plane through the Earth's axis that is perpendicular to the Earth's plane of orbit ALSO passes through the sun itself (i.e. the Earth's rotation axis is lined up with the sun, north end closest) is the summer solstice. When the same plane passes through the sun again, only with the south pole closest, that is the winter solstice. At summer solstice, the length of the day is longest in the northern hemisphere. At winter solstice the day is shortest in the northern hemisphere. The opposite is true in the southern hemisphere. On the equator the lengths of the days don't change at all! The further you get from the equator, the more the length of the days change with the seasons.\n\nSo let's talk northern hemisphere. If the longest day is around June 21 (summer solstice) and the shortest day is Dec 21 winter solstice, you can think of the length of the days as changing smoothly from shortest to longest as you move from winter to summer solstice. If you do the geometry to figure out how the length of days changes with the seasons, it looks a lot like a sine wave. It's actually shaped a little differently because the Earth's orbit is not a circle--that would make a sine wave exactly for the length of days--but instead an ellipse. But it's still pretty close to a sine wave. If you look at a sine wave, you'll notice that as the wave approaches the bottom, slows down its descent until it almost "flattens" at the bottom, but not quite. Then after the bottom, it goes up more steeply until somewhere in the spring it is changing as fast as possible (pretty near to the vernal equinox), then begins to slow down again until it hits the peak at the summer solstice. After the summer solstice, the longest day, the length of days begins to fall, slowly at first and then ever faster, until somewhere in fall (pretty near the autumnal equinox) it's changing as fast as it's ever going to. Then it begins to slow down, until it hits the minimum at the winter solstice again. If you look back at the description about, you'll notice that the rate at which the length of days change also varies with the season. In fact, the rate of change is like a sine wave, too, only it's shifted by a season from the wave that describes the rising and falling of the length of the day itself.\n\n\nFor the latitudes farther away from the equator, the amplitude of the sine wave is larger. For the southern hemisphere it is flipped upside down compared to the same latitude in the northern hemisphere. And on the equator, the "sine" curve as zero amplitude--that is, it's a straight line.\n\nIn calculus you would say that the rate of change of a function (the "derivative" of the function with respect to time) tells you how fast the daylight is changing on a given day. And, in calculus you also learn that the rate of change of a sine wave is a cosine wave--or just another sine wave shifted back by 90 degrees. And 90 degrees of the sine wave describing the length of days corresponds to one season on Earth!
526984
NO, angle of the earth on it's axis limits sunlight for a few months. The days never warm up.
880804
You have it! The Earth is tilted 23 degrees over relative to its orbit of the Sun. This spinning makes first the North Pole, and then the South Pole point towards the sun 6 months later. To our eyes, the Sun seems to rise and set in different spot each day. It is our point of view, together with the current location of Earth in its orbit.\n\n;-D Yes. This is what causes the seasons.
624280
There are two solstices each year, summer and winter. The summer solstice is the longest day of the year. The winter solstice is the shortest day of the year. In the Northern hemisphere this happens right around June 21 (summer) and December 21 (winter) in the Southern Hemisphere these dates are reversed. The dates vary slightly year by year, of course, because the sun doesn't pay attention to our calendar.\n\nLikewise there are two equinoxes in the year, Autumn and Spring. These are the days when the hours between sunrise and sunset and sunset and sunrise again are of equal length. That is, the day and night are the same. These occur right around March 20th (vernal/spring) and September 21st (autumnal/fall). Again, it's reversed in the Southern Hemisphere and dates vary.
846393
Actually, it's "equinox" that means equal night.\n\nOn the equator, the days and nights are always 12 hours long (not exactly, the width of the sun's disk plus the effects of atmospheric refraction make the days a few minutes longer than the nights). The tilt of the earth's axis affects the path the sun takes across the sky, but not the length of the day.\n\nOn the equinoxes, and at no other time, the length of the day and night is 12 hours the whole world over (except right at the poles), because the plane containing the tilt of the earth's axis is at right angles to the direction between the earth and the sun - that is, the axis is not pointing at all toward or away from the sun, and the poles are equidistant from the sun.
638263
the earth is spinning on a tilted axis (23.5 degrees), therefor sunlight is not equally dispersed, causing seasons... look up seasons on wikipedia and it will give an explanation i'm sure
132625
A day is 24 hours long. However, the amount of daylight varies tremendously. In summer, there is 24 hours of daylight in the Midnight Sun period. In midwinter, there is polar night where the sun never goes over the horizon.
667259
Seasons aren't physical things. Humans partitioned an otherwise seamless and continuous cyclic event into 4 convenient sections to better describe ans deal with it.\n\nAlso, not all parts of the world have 4 seasons. Near the equator, they don't really have any or maybe just two. The further away from the equator you get, the more pronounced the annual cycles get. Extreme at the poles.
378736
Keep in mind, things like seasons, months, minutes, etc, are human contructs- we can define them anyway we like.  Earth doesnt really neatly divide the year into 4 parts, humans do-
951750
The two equinoxes (fall and spring) determine when the sun starts moving in the other direction and the two solstices (winter and summer) determine the shortest and longest days.  Your observation should continue to move in the direction as previously observed, but due to daylight savings time, the time will change...so get up earlier than 7 am to see what you want to see (sunrise for you will be at 7:14 am).
238896
The months are lunar (based on the moon) and a year is solar (based on the sun). The numbers are dependent on the revolution of the earth around the sun and the moon around the earth. \n\nIf you are referring to the fluctuating number of days in a month, the Romans did this in order to get the lunar and solar calendars to match. \n\nThe more intriguing question is: who thought up the weekly cycle?
269206
It's the angle of the earth's rotation.  The northern hemisphere tilts away from the sun during winter, causing long periods of darkness, and towards the sun in summer, causing longer daylight hours.  At the extreme nothern latitudes, this leads to constant daylight or constant darkness at those times of the year.
807256
The Egyptians and Babylonians decided to divide the day from sunrise to sunset into twelve parts that are called hours. They also divided the night, the time from sunset to sunrise, into twelve hours. But the day and the night are not the same length, and the length of the day and night also changes through the year
888338
It is actually because of the Earth's orbit in space around the sun that we have seasons to begin with... \nThe seasons result from the Earth's axis being tilted at an angle of approximately 23.5 degrees of arc; thus, fluctuating the amount of exposure to the sun. \n\nClick the links below for more information.\n\nThis is why is appears to us that the constellations are changing.\n\nhttp://www.astro.wisc.edu/~dolan/constellations/constellationmonth_list.html
1023272
Really, I'd think the opposite, because the days are becoming longer, if you are in the Northern Hemisphere, because the sun is staying "up" longer than when it is winter.  I also heard, a few years ago, and I don't remember if this is true or the opposite way around, but that the days were becoming longer becasue of the speed that we are turning in.  It said that like in10000 years the day will be hours longer than now.