It is known that on Earth there are four seasons: winter, spring, summer and fall. And, season in the Northern hemisphere is always opposite to season of the Southern hemisphere. Why on the planet there is regularly a change of seasons?
The change of seasons is caused astronomically at the expense of a planet inclination in relation to the axis of rotation. The axis of rotation is the imagined line passing through the center of Earth between Northern and Southern poles which serially are turned to the Sun in process of the movement of the planet around it. On poles of Earth there are only summer also winter seasons. In summertime of year in polar regions sun shines day and night: both in the afternoon, and at night. This geographical phenomenon received the name of polar day. In the winter in the Polar region there comes the polar night which is characterized by darkness which lasts for all day. Seasons do not change on the equator because this line passing through the center of Earth is most removed from planet poles. That is the equator is perpendicular to an axis of rotation of Earth therefore sunshine warm at all seasons of the year the earth's surface of the equator to the maximum. The equatorial belt is famous in the eternal summer and heat. Here amplitudes of temperature differences for all year are extremely small. Change of seasonality is provided in other climatic zones. When the top of the North Pole is turned to a star, in the Northern hemisphere the summer season begins while in Youzhny the winter season is observed. In half a year there is a reverse situation. The summer comes to the Southern hemisphere, and the Northern hemisphere appears in the power of winter. The fall and spring are transitional seasons. Off-season begins then, the planet stays in an intermediate position in relation to a star. It should be noted what influences climatic features of any given country not only an inclination of Earth concerning a rotation axis. It is necessary to take into consideration currents, air masses, a relief of the earth's surface, short-term meteorological factors.