How Earth's seasons change?

Earth’s axis is an imaginary pole going right through the center of Earth from “top” to “bottom.” Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth’s surface gets some of each.The seasons are caused by the Earth being tilted on its axis by an average of 23.5 degrees (Earth’s tilt on its axis actually varies from near 22 degrees to 24.5 degrees).The Earth has an elliptical orbit around our Sun. The Earth is at its closest point distance wise to the Sun in January (called the Perihelion) and the furthest in July (the Aphelion). But this distance change is not great enough to cause any substantial difference in our climate. This is why the Earth’s 23.5 degree tilt is all important in changing our seasons. Near June 21st, the summer solstice, the Earth is tilted such that the Sun is positioned directly over the Tropic of Cancer at 23.5 degrees north latitude. This situates the northern hemisphere in a more direct path of the Sun’s energy. What this means is less sunlight gets scattered before reaching the ground because it has less distance to travel through the atmosphere. In addition, the high sun angle produces long days. The opposite is true in the southern hemisphere, where the low sun angle produces short days. Furthermore, a large amount of the Sun’s energy is scattered before reaching the ground because the energy has to travel through more of the atmosphere. Therefore near June 21st, the southern hemisphere is having its winter solstice because it “leans” away from the Sun.On the winter solstice near December 21st, the Sun is positioned directly over the Tropic of Capricorn at 23.5 degrees south latitude. The southern hemisphere is therefore receiving the direct sunlight, with little scattering of the sun’s rays and a high sun angle producing long days. The northern hemisphere is tipped away from the Sun, producing short days and a low sun angle.