Why are there seasons?
The changing of the seasons is eternal and unchanging phenomenon. The reason it is the motion of the Earth around the Sun.
The path in space moves the globe is shaped like an elongated circle - ellipse. The sun is not in the center of this ellipse, and in one of her tricks. Therefore, throughout the year, distance from the sun to the Earth periodically changed: from 147,1 million km (in early January) to 152,1 million km (in early July). The transition from the warm season (spring, summer) for the cold season (autumn, winter) occurs not because the Earth approaches the Sun, it is removed from it. But today so many people think! Look at the above figures: in June, the Earth is farther from the Sun than in January!
The fact that the Earth, in addition to the circulation around the Sun, revolves around an imaginary axis (the line through the North and South poles). If the Earth's axis is positioned at a right angle to the Earth's orbit around the Sun, we would not have seasons, and all days were the same. But this axis is tilted towards the Sun (23°27'). The result is that the Earth revolves around the Sun in an inclined position. This situation persists year-round, and the Earth's axis is always directed towards a single point on the Polar star.
Therefore, at different times of the year the Earth is different substitutes sunlight its surface. When the sun's rays fall vertically, right, the Sun hotter. If the rays of the Sun falling on the earth's surface at an angle, they warm the earth's surface is weaker.
The sun is always directly on the equator and in the tropics, so the inhabitants of these places don't know cold. There is not as sharply as we do, seasons change, and it never snows.
At the same time of the year each of the two poles turned to the Sun, and the second part is hidden from him. When the Northern hemisphere is facing the Sun, in the countries North of the equator, summer and day long, South - winter, and the day is short. When the direct rays of the Sun fall on the southern hemisphere - here comes summer, and in the Northern winter.
The longest and the shortest days of the year are called days of the winter and summer solstice. The summer solstice occurs 20, 21 or 22 June, and the winter is 21 or 22 December. And yet all over the world each year there are two days when day and night are of equal. It occurs in spring and autumn, exactly between the days of the solstice. In the autumn of this occurs around September 23 is the autumn equinox, in the spring, about March 21 is the vernal equinox.
By the way...
In hot countries, too, is the changing of the seasons, she only expressed differently, not like us, in the middle latitudes.
In India, winter is a time of severe drought, which affects all living things. At this time, blow the winter monsoon - from land to sea. In the spring, monsoon change direction, they begin to blow from sea to land, bring moisture, rich, nourish moisture to dry, parched earth. Nature comes alive. The rainy season. And the rains there pour buckets - no private jets, and a continuous stream!
A little different from other seasons in the Far North in the Arctic, or in the Extreme South in the Antarctic. There is always winter. This heat is never, and the snow only some thaws from the top, exposing the frozen ground. The difference from winter summer is the amount of light, not heat. In spring and summer, the Sun moves across the sky all day, not below the horizon but its rays Shine though is good and warm bad: they fall obliquely, as if scratching the surface.
And still at high Northern latitudes is something similar to our spring and summer, some even bloom modest Northern flowers, and on the rocky Islands of the Northern seas sea birds nest.
In Antarctica at this time of winter, severe frosts and winds. Is the polar night. In the summer there comes the sun, and it shines day and night, but the heat from it will not be added. In the southern hemisphere at high latitudes climate where harsh than in the North. Above zero temperature never rises.