The seasons naturally change our world as time progresses, creating constant renewal on Earth.
The seasons are a fascinating phenomenon that we experience all over the world. As the Earth revolves around the Sun,… Axial tilt Creates differences in Amount of sunlight Which we receive at different times of the year. These differences lead to seasons, however, When exactly do the seasons start in the Northern and Southern Hemisphere?
In this article, we will analyze in detail the cycle of seasons and when we can welcome spring, summer, fall and winter in different parts of the world.
Cycle of seasons
In order to understand when the seasons begin, we must first understand Why did it happen? Seasons are the result of two main factors: The tilt of the Earth’s axis and its orbit around the Sun.
- Earth’s axis tilt: The Earth’s axis of rotation is not perpendicular to its orbit around the Sun It is tilted at an angle of approximately 23.5 degrees. This tendency is what creates the seasons. As the Earth revolves around the Sun, Different areas receive sunlight at different angles, Which leads to changes in temperature and length of days.
- Earth’s orbit around the sun: The land takes approx 365.25 days In completing an orbit around the sun, this orbit is not a complete circle, however Ellipse, Which means that the Earth It’s not always the same distance from the sun.
When does spring start?
In the Northern Hemisphere: Spring has officially begun About 20 or 21 March. This moment marks the vernal equinox, when day and night are approximately equal in length. From here, the days begin to lengthen and temperatures begin to rise.
In the Southern Hemisphere: As for the Southern Hemisphere, the vernal equinox occurs Around September 22nd. As in the Northern Hemisphere, this is the date when spring officially begins, and the days become longer and warmer.
When does summer start?
In the Northern Hemisphere: The summer solstice usually marks the beginning of summer in the Northern Hemisphere Around June 20th or 21st. On this day, the northern hemisphere tilts toward the sun, resulting in the longest day of the year.
In the Southern Hemisphere: In the Southern Hemisphere, the summer solstice occurs Around December 21st or 22nd. Currently, the southern hemisphere is tilted towards the sun, which means it has its longest day and the beginning of summer.
When does fall start?
In the Northern Hemisphere: The autumn equinox marks the beginning of autumn in the Northern Hemisphere, usually around September 22 or 23. During this time, the length of day and night is approximately equal.
In the Southern Hemisphere: In the Southern Hemisphere, the autumn equinox occurs About 20 or 21 March. As in the Northern Hemisphere, this is the date when autumn officially begins.
When does winter start?
In the Northern Hemisphere: The winter solstice usually marks the beginning of winter in the Northern Hemisphere Around December 21st or 22nd. On this day, the northern hemisphere is tilted away from the sun, resulting in the shortest day of the year.
In the Southern Hemisphere: As for the Southern Hemisphere, the winter solstice occurs Around June 20th or 21st. This is the shortest day of the year in the Southern Hemisphere and marks the beginning of winter.
Climate change and seasons
It is important to note that although the above dates are Official dates at the start of the seasons, Climate changes may vary depending on geographical location. Moreover, climate change has occurred in recent years Significant impact on duration and intensity Seasons (temperature level) in many parts of the world.
Seasons of the year: their tendencies and equations
The seasons, which seem natural and predictable, are actually the result of wonderful mechanisms Our solar system and terrestrial geophysics. Through centuries of observation and study, humanity has figured this out Understand scientific processes accurately Which governs the annual cycle of the seasons. Here are some key aspects of this cosmic dance and related discoveries:
- Earth’s axis tilt: One of the basic concepts behind seasons is the tilt of the Earth’s axis. The Earth does not rotate exactly perpendicular to its orbit around the Sun, but rather its axis is tilted inward Angle is about 23.5 degrees. This tendency is the reason we experience Seasonal changes in the amount of sunlight In different parts of the world throughout the year.
- Solstices and equinoxes: The solstices and equinoxes are crucial events in the cycle of the seasons. The summer and winter solstice represent the days in which… The Earth’s north pole is tilted more toward or away from the sun. Which results in the longest or shortest day of the year, respectively. The spring and autumn equinoxes occur when the Earth’s axis is tilted It does not lean toward or away from the sun. Which leads to equal days and nights.
- Earth’s elliptical orbits: Although the tilt of the Earth’s axis is a major factor in creating the seasons, the elliptical shape of the Earth’s orbit also plays an important role. The Earth moves faster in its orbit when it is closer to the Sun (perigee) And slower when far away (Apogee). This means that the stations They do not have a uniform duration. Winter, for example, is slightly shorter in the Northern Hemisphere than summer.
- Astrological developments and calendars: Throughout history, astronomers have… Accurate notes and calculations To predict the exact times when solstices and equinoxes occur. This has led to the development of accurate calendars, such as the Gregorian calendar, which is used in most parts of the world Synchronize the calendar year with the solar year.
- Impact on the environment and agriculture: Knowledge of the seasons was crucial to agriculture and the environment. Seasons are determined When are they planted and harvested, and how organisms adapt to them to changes in temperature and sunlight. Scientists are also studying how climate change could affect the seasons and their consequences.
Why do seasons differ in the two hemispheres?
Seasons differ in the two hemispheres due to the tilt of the Earth’s axis.
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