Seasons on Earth differ between the Northern and Southern Hemispheres due to the planet’s axial tilt and its orbit around the Sun. This natural phenomenon explains why countries in the Northern Hemisphere, such as the United States, China, India, Afghanistan, Tajikistan, and other Central Asian countries, experience winter, while Australia and other Southern Hemisphere nations enjoy summer during
December.
The Role of Earth’s Tilt
The Earth’s axis is tilted at an angle of 23.5 degrees relative to its orbital plane. This tilt is the main reason
for the seasonal changes. As the Earth revolves around the Sun, the tilt causes different hemispheres to receive varying amounts of sunlight at different times of the year.
Importantly, the shape of Earth’s orbit—though elliptical—does not play a significant role in seasonal changes. In fact, Earth is actually closest (5 million kilometers lesser than the summer months of june) to
the Sun during early January, when countries like India, China, Afghanistan, Tajikistan, and other nations in Central Asia experience winter. This might seem counterintuitive, but it is the axial tilt, not the distance from the Sun, that determines the seasons.
How Seasons Are Determined
- December Solstice (the point at which one hemisphere is tilted most directly toward the Sun, resulting in the longest day of the year in that hemisphere): In December, the Southern Hemisphere
is tilted toward the Sun, while the Northern Hemisphere tilts away. - The Southern Hemisphere experiences summer, with countries like Australia, South Africa, and Argentina enjoying longer days, shorter nights, and warmer temperatures.
- Meanwhile, the Northern Hemisphere experiences winter, with nations like China, India, Japan, Central Asia and the United States receiving less direct sunlight, leading to shorter days and colder weather.
- June Solstice (the point at which the Northern Hemisphere is tilted toward the Sun, creating the longest day of the year in the Northern Hemisphere): The situation reverses in June, with the Northern Hemisphere tilted toward the Sun, resulting in summer for countries like India, China, and the U.S., while the Southern Hemisphere endures winter.
The Effect of Sunlight
The tilt also affects how sunlight reaches the Earth:
- Day Length: In winter, Northern Hemisphere countries, including those in Asia and Central Asia, have shorter days and longer nights. Conversely, during summer in the Southern Hemisphere, countries like Australia enjoy extended daylight hours.
- Sun Angle: During winter, the Sun is lower in the sky in countries like Afghanistan, Tajikistan, India, and China, spreading its energy over a larger area and making the temperatures cooler. Conversely, during Southern Hemisphere summers, the Sun is higher, concentrating heat in places like Australia and Argentina.
Summary
The contrast between winter in Northern Hemisphere nations like Afghanistan, Tajikistan, China, Japan, India, and the United States, and summer in Southern Hemisphere countries like Australia, is due to Earth’s axial tilt, not its distance from the Sun. Even when Earth is closest to the Sun in January, countries in Central Asia and other Northern Hemisphere regions experience winter because they are tilted away
from direct sunlight. The axial tilt causes the hemispheres to alternately lean toward or away from the Sun during its orbit, changing the intensity and duration of sunlight they receive
Article By: Ibn Qalam
About the Author: Ibn Qalam is a budding writer with a keen interest in environmental issues, science and technology, and social matters. He is a contributor to The KashPost