Question

briefly explain the the occurrence of season with suitable diagram
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Answer 1

Answer:

We have hot summers and cold winters because of the tilt of the Earth's axis. The tilt of the Earth means the Earth will lean towards the Sun (Summer) or lean away from the Sun (Winter) 6 months later. In between these, Spring and Autumn will occur. ... The Earth's movement around the sun causes the seasons.

Answer 2

the earth’s orbit is an ellipse and included a nice diagram of that, which I will reproduce here:


Note that we here in the northern hemisphere have summer when the earth is farthest from the sun and winter when we are closest to the sun, thus making our summers a bit cooler and our winters a bit warmer. The opposite is true for the southern hemisphere: warmer summers and colder winters. However it has been suggested that since there is so much more water in the southern hemisphere that the water moderates the seasonal temperature swings better down under than it would up here.

I would like to change the original question, tho, to be this:

WHY do seasons occur on Earth?

We have seasons because of the tilt of earth’s axis. But WHY is the earth’s axis tilted in the first place? The answer, it would appear, is that about 4.5 billion years ago a Mars-sized planet collided with the proto-earth. Astrophysicists today call that hypothetical planet Theia.

That collision did a number of things which are consistent with what we know today about the earth and the moon. It splashed out debris which became our moon (with a side effect of slowing and stabilizing the subsequent rotation of earth). It added a lot more iron to earth’s core thus giving earth more gravity and a stronger magnetic field (with the side-effect of protecting our atmosphere from being stripped away by the solar wind). It spun the earth so that we have days and nights, thus evening the heat distribution across the globe. Lastly it tilted the axis of earth’s rotation and made our orbit a bit more of an ellipse, and thus we have seasons.

Had that collision not occurred the earth, like Mars, would have no atmosphere and no water. It might be tidally locked to the sun (hot on one side, cold on the other). And there would certainly be no life on earth, including no us. So, all in all, three cheers for Theia!