Explanation: The Earth's axis is not completely vertical, but is inclined towards the horizontal, which causes some parts of the Earth to be closer to the Sun, i.e. receive more sunlight than other parts. This means that the hemisphere, which at a given time is inclined towards the sun, has more hours of sunlight during the day, the sun is closer to that hemisphere and then a summer is in that hemisphere.
For example, when the northern hemisphere is inclined towards the sun due to the inclination of the axis, then at all points of the northern hemisphere is summer, i.e. at latitudes between the equator and the north pole. This again means that at all points in the northern hemisphere, the temperatures are not the same, but it depends on latitude in the northern hemisphere. At the points of the hemisphere closer to the equator, temperatures are higher than those near the north pole, although in the entire northern hemisphere, therefore, both near the equator and near the north pole, at the same time is summer.
The same is true of the southern hemisphere when it is tilted towards the Sun. The angle of inclination of the Earth's axis toward the Sun determines the seasons, the amount of sunlight, and that it will be either day or night, since the Earth also revolves around its own inclined axis. This means that, for example, in the northern hemisphere, which inclined toward the Sun at that moment, it is summer, with a certain number of hours of sunshine, but it can also be night.