The Four Seasons .. How do they occur?

Arab Weather - The seasons are defined as periods of the year that are characterized by special climatic conditions, where four seasons alternate on some parts of the earth, each of them regularly every year, the earth receives different amounts of sunlight and heat in each season, and the hours of night and day differ in the days of each season, and it occurs The four seasons are mainly due to the rotation of the earth around the sun, and the tilt of the earth's axis during rotation.

The Earth’s axis is an imaginary line that connects between the Earth’s North Pole and the South Pole through the center of the Earth. The Earth’s axis is tilted by 23.4 degrees, and the Earth revolves around it every day a complete rotation, and this rotation results in the alternation of night and day, just as the Earth moves in an elliptical path around the sun, which results The four seasons, and because of the elliptical shape of the Earth's orbit around the sun, the Earth passes through two points that are farthest from the sun (apogee), at which the winter and summer solstices occur, and the closest two points (perihelion) occur at the spring and autumn equinoxes.

The date of the four seasons began

Summer and winter: the astronomical winter begins in the northern hemisphere on December 21 or 22, when the Earth is at its apogee, and its axis is from the north at its maximum mile away from the sun, and thus the sun descends in the sky of the northern hemisphere And its rays spread over wider areas, and this means that every spot in those areas receives less energy, so temperatures begin to decrease, and this continues during the three winter months until the day of the spring equinox.

The opposite occurs in the southern hemisphere, so that the 21st or 22nd of December is the day of the summer solstice and the date of the beginning of the summer season, so temperatures begin to rise in the regions of the southern part of the globe.

As for the summer season in the northern hemisphere, it begins on 20 or 21 June when the Earth is at the other apogee, and its axis is from the north at its maximum inclination towards the sun, and thus the sun rises in the sky of the northern hemisphere, and its rays are spread over areas Less, and this means that every spot in those regions receives more energy, so temperatures begin to rise in the northern hemisphere regions, and the three summer months extend until the autumn equinox day. The exact opposite happens in the Southern Hemisphere, so that on June 20 or 21, the start of the winter season.

Spring and autumn: spring begins in the Northern Hemisphere on 20 or 21 March / March, when it reaches the Earth - to - trough point in its orbit around the sun, then perpendicular to the sun 's rays with the equator of the Earth line, the day of the spring equinox, which is equal to the hours of day and night And then the sun's rays begin in the direction north of the equator, and the spring season continues until the day of the summer solstice in the month of June , and the autumn season begins in the northern hemisphere on September 22 or 23, and then the sun's rays are also perpendicular to the equator of the Earth, which is The day of the autumn equinox, in which the hours of night and day are equal, after which the sun's rays begin towards the south of the equator, and the autumn season continues until the day of the winter solstice in the month of December.

In the Southern Hemisphere, spring begins on September 22 or 23, and autumn begins on March 20 or 21.

Do all parts of the globe witness the four seasons?

The four seasons occur in temperate and sub-polar regions. As for the tropics close to the equator, some of them witness one hot season throughout the year, and others only alternate with two seasons, a dry season and another rainy season, and there are no signs of cold or snow, due to the slight change. Because of the angle of sunlight falling on those areas during the rotation of the earth around the sun, and the dry season is characterized by high temperature, with very little (or no) amount of rain, and this season continues most of the months of the year, but in the rainy season the regions witness abundant rainfall, and this season continues From 2 to 3 months, the dry and rainy seasons alternate between the regions north and south of the equator, and the further we move from the equator, the greater the difference between the seasons, as well as the polar regions that witness two seasons a year; A winter in which the sun is completely absent and does not shine most of the winter, and a summer in which the sun shines throughout the summer months and never sets.