Initially, it is possible to think that the Earth, rotating around the Sun along the elliptical orbit, at the time of the greatest removal from our star gets the least heat, because we have winter. But if a warm summer day is on the plane and fly to another end of the world, then, going down the ladder, you will regret that you have not taken more warm clothes with you. Around will be much colder than in the place where you flew from.
And if you open the solar system scheme, you can be very surprised, seeing that it is in winter our planet flies closest to the sun.
So what is the case? The answer is very simple: angle of inclination. The fact is that the Earth rotates around its axis under and tilted to the Sun at an angle of 23 degrees. Thus, from spring to autumn, the northern hemisphere lies to the sun at a more direct angle and gets more heat than the southern one, and from the fall in the spring, sunbathing is already taking a southern hemisphere. It is very easy to understand this, looking at the picture from above.
The equator throughout the year is under almost a direct angle in relation to the sunshine, so the change of seasons there is almost imperceptible. At the same time, the rays of the sun are always taking advantage of the poles of our planet. That is why they never run snow and is always cold.