why do we have seasons?

Question

why do we have seasons
like autumn leaves fall of trees
winter its cold
spring trees grow
summer its hot
and what months of the year are the seasons

Answer 1

This is because the earth flies round the sun once a year while also rotating around a line (an axis) drawn through the centre of the earth from North Pole to South Pole once every 24 hours (at a rotation rate of 15 degrees of longitude an hour to make 360 degrees in 24 hours). This spinning of the earth has a "gyroscopic" effect like a child's spinning top, which means that the earth has very large forces holding it at a constant angle and "attitude" in space in its rotation, regardless of where it is on the yearly journey around the sun.
The flying round the sun gives us the solar year from January to December, and the spinning of the earth every 24 hours gives us night and day (it's night for the time that the sun is on the other side of the earth from us).

Now comes the tricky bit.
If the spin line pole to pole was at the same angle to the sun throughout the year, so that the sun always appeared to be bang over the equator thoughout the year, then most of the earth would have a standard day and night throughout the year (except for the North and South polar regions which would have no light at all at any time because the light from the sun can't bend round the curve of the earth to light and heat the regions at the pole (to understand this better, imagine that the sun is a point of light, but the earth is a ball, draw a diagram of this setup, and see that light travelling in a straight line from the "point" of the sun can't reach the top and bottom of the ball).

This setup of itself wouldn't give us the seasons. Instead the equator would be very hot, and there would be a gradual lessening of the sun's heat effect as the angle the sun's heat/light hit the earth "fell away" from a right angle at the equator, to almost parallel towards the poles (this is a similar effect to the long shadows in the evening and the morning, as the sun just rises and sets, but the daily pattern of length of those shadows would be the same throughout the year on any one point on the earth, and it would not change). There is another example that could be used so that you could picture this effect, which someone who knows about equatorial communications sattelite "footprints" on the earth could explain to you.

Last lap now, I hope!
The seasons happen because the spin axis from pole to pole is NOT at right angles to the equator but instead is at an angle of 23.5 degrees from a right angle. So, even though the spinning earth is going round the sun each year, if you stood on the same spot in the Northern part of the world throughout that year, then the sun, from January to June would appear to go higher in the sky each day before moving down again towards sunset at night, and would appear to rise lower in the sky each day from June to December. In the Southern part of the world the sun would appear to rise increasingly higher in the sky from June to December, and increasingly lower in the sky each day from December to June. This is because the spin axis is canted over 23.5 degrees from the sun.
The heat hitting the earth at any one particular spot depends on the angle that the sunlight hits the earth, which depends on how near to "sun directly overhead" it gets each day. So in the Northern part of the world more heat hits the earth each day from December to June so it generally gets hotter each day, and less heat hits the earth each day from June to December so it generally gets colder each day. The reason that it continues to get hotter in July and August, before tailing off in September/October is because the point on the earth heats up gradually, and cools down slowly, so there is a lag in the delivery of heat before the hottest months of July/August.

So that's the mechanism then, I hope it is fairly clear. You should be able to see that there is a yearly cycle of heating and cooling going on as the "sun overhead" point appears to move North from the Equator to the Tropic of Cancer (at 23.5 degrees North), from March (start of Spring in the North, start of Autumn in the South) to June each year (mid-Summer and longest day in the North and mid-Winter and shortest day in the South), and then appears to start moving South again from the Tropic of Cancer, to the Equator by September (start of Autumn in the North, start of Spring in the South, equal night and day in both), and then further South to the Tropic of Capricorn at 23 degrees South by December (mid-Winter in the North, mid-Summer in the South), before starting the whole cycle again.
The actual dates are -
Spring Equinox (equal night and day in the North and South, moving North, "sun overhead" point at the Equator) - March 21st.
Summer Solstice (longest day in the North, "sun overhead" at the Tropic of Cancer 23.5 degrees North, "sun overhead" point starts moving South again) - June 21st.
Autumn Equinox (equal night and day in the North and the South, "sun overhead" point at the Equator, Zero degrees, moving South) - September 21st.
Winter Solstice (shortest day in the North, longest day in the South, "sun overhead" point at the Tropic of Capricorn, 23.5 degrees South, "sun overhead" point starts moving North again) - December 21st.
Spring Equinox, at the Equator, March 21st, cycle begins again.

Finally, you may have heard of the "land of the midnight sun". This is the area of the earth at the North pole, (and the South pole at the opposite end of the year) which is illuminated increasingly by the sun from March till September, and the sun is at its "nearest" on June 21st (the zenith). For some time before and after June 21st, in this area, the sun shines "over the top" of the pole and illuminates the area that would normally be in darkness, so the sun never sets, even though further round the earth to the South it is night-time . This area is bounded by the Arctic Circle. Within the Antarctic circle, at the other end of the earth the sun never rises at this time. The whole thing happens in reverse at the Antarctic end from September to March.

Answer 2

the earth rotates around the sun every 12 months, thus exposing the earth to different angles of the year and how far we are from the sun. this give us our Earth-Sun line changes throughout the year. Twice a year, at the spring and fall equinox (around March 21 and September 22--the exact date may vary a bit) the two directions are perpendicular. Twice a year, the angle is as big as it can get, at the summer and winter solstices, when it reaches 23.5 degrees. In the summer solstice (around June 21) the north pole is inclined towards the Sun, in the winter solstice (around December 21) it faces away from it.

Answer 3

Just after the earth was formed and became part of a large Galaxy, it found its way into a system of sun and moon and stars and things like atmosphere and gravitational pull and layers of stratosphere and layers of earth and all of the magic things which grow upon it. Why do we have seasons? Like even some of the animals, the earth has a shedding and a rebirth period, hence the seasons bring this all about. In different parts of the world, the seasons have different days they begin on, look at your own home place calendar, but there are things like global warming or even global cooling and pollution and things like that and even storms and things like that which can delay a season or even make it happen faster -- like making it a colder winter season.
The Pink Lady

Answer 4

long time ago, when the solar system was still gettin built a big asteroid (1/4 the size of the earth) encountered with the young aged earth. so the consequence of that impact was to rotate the axis of the earth from 0 degrees to the current form, which means that after that impact a part of the earth were closer to sun and the 4 eras were born

Answer 5

Since the first question has been answered already , I will answer the other one
I live in Western Australia. The seasons start officially as below :
Spring 1st Sept
Summer 1st Dec
Autumn 1st March
Winter 1st June

Answer 6

It's always mating Season in these parts...

Answer 7

because the earth rotates around the sun every 12 months, thus exposing the earth to different levels of solar radiation.

Answer 8

gosh we dont' have all the seasons in some states. like texas lower part we dont' have fall and winter or whatever. sometimes spring comes for few weeks and then sometimes its hot right away. naturally we're suppost to have fall oct nov and then winter dec, jan feb. may is spring and april its sorta like that but it differs where you live if you are in different states.

Answer 9

because Earth rotates and counties are located in diff parts of the world

Answer 10

It is due to the Globe is slantic.