what causes the four seasons on earth?

Answer 1

the revolution of earth around the sun, and the tilt of the earth's axis 23.5 degrees.
the website below has diagrams that may help explain it a little better. =)

Answer 2

http://www.scienceu.com/observatory/articles/seasons/seasons.html

"Seasons reasons
Unless you live near the Earth's equator, you have no doubt noticed that the weather changes during the year: it is hotter during the Summer, colder in Winter, and somewhere in between during Spring and Fall. These are the seasons, a regular change in temperature, that repeat themselves every year, more or less regularly.

What causes these changes? The Sun is our main source of heat, and since these changes are the same every year, it surely has something to do with the movement of the Earth around the Sun. If we get closer to a fire, we get hotter. Could it be then that the Earth gets closer to the Sun during Summer, and farther during Winter? This idea seems at first to have some merit, until we remember that the seasons get reversed when we cross the equator: when it is Summer in the northern hemisphere, it is Winter in the southern one, and vice versa. And surely Argentina is at the same distance from the Sun as the USA!

Besides, that the Earth's orbit is an ellipse, not a circle, so that at some times the Earth is closer to the Sun than at others; but this ellipse is very nearly a circle, and the relatively small differences in distance to the Sun cannot account for the changes in temperature. And to make things worse, the Earth is closer to the Sun during the northern hemisphere Winter!

What, then, is, the cause of the seasons?

In the above animation, you can see the Earth during one full year (the animation then starts over again), as you would if you looked straight at it from the Sun. As you can see, the part of the Earth that is directly facing the sun changes with the time of the year. It is the northern half for a while, then moves south of the equator, only to move back to the north again.

What causes this? The Earth rotates around an imaginary line passing through the poles, called the axis. This line forms an angle (called the tilt) of 23.4° with the perpendicular to the orbit of the Earth around the Sun.

As the Earth moves around the Sun, this axis stays always pointing in the same direction. This means that, during part of the year, the northern part of the Earth will lean more directly against the sun, and during other parts the southern part will.

What has this to do with temperature? Well, when the northern hemisphere is leaning away from the sun, the rays coming from it hit this part of the Earth at a smaller angle than on other parts of the world. This means that the same amount of light is distributed over a larger surface, and therefore these places receive less heat than the others. The southern hemisphere is experiencing Summer, the northern hemisphere Winter. In half a year, the situation reverses, and it is now Winter in the southern hemisphere since that part of the earth is now leaning away from the sun.

The seasons are then the result of this tilt of the Earth's axis. If the tilt of the Earth's axis was 0° there would be no difference in how the rays from the sun hit its different regions, and there would be no seasons.

Not all planets have the same kind of tilt as the Earth has: Uranus, for example, has a tilt of almost 98°. Its axis, then, lies almost on the plane of its orbit, and a day there lasts about as much as one year on Uranus: about 84 Earth-years."

Answer 3

The most significant cause is the tilt of the earth's axix relative to the eclyptic (the plane on which the earth travels around the sum). So, away from the equator, in summer the sun's rays hit the earth more perpendicular to the surface and therefore pass through less absorbing atmosphere than in winter, when they hit the earth at a shallower angle and therefore pass through more atomosphere. Also, the same amount of energy in summer hits a smaller area of earth than in winter, where the area hit is larger. Have a search on the internet - it's much easier to understand with diagrams.

Wikipedia has some decent diagrams.

Answer 4

there are a lot of things that contribute to the seasons on this planet. for instance, the earth tilting on it's axis, the rotation , the moon in our orbit, solar flares given off by our sun( which create solar winds which pass through and around our planet, the other planets in the solar system and the orbit around the sun, and don't forget the asteroids and other flotsom passing through our solar system. these things all have a contributing effect on our four seasons.

Answer 5

The earth's tilt...
It tilts towards and away the sun causing the different seasons.

Answer 6

The orbit of the earth around the sun, and the earths "wobble" as it rotates. I think.