How Earth’s Axis and Orbit Shape Its Seasons

Context:

The axial inclination and orbital eccentricity of earth influence its climatic adaptations and seasonal variations. While axial tilt is the primary insolation contributing factor for seasons on earth, a new research is beginning to demonstrate that the elliptical nature of earth’s orbit might cause significant differences in just temperature or precipitation.

Earth’s Tilt and Seasonal Changes

• Tilt of the earth affects seasons
  • While the Northern Hemisphere is tilted toward the Sun, it experiences summer.
  • Otherwise, the Southern Hemisphere has a summer when that hemisphere is hematemically tilted toward the Sun.
  • This tilt is the predominant factor in seasonal changes.

Orbital Eccentricity on Earth and Climate

• It is not true that the orbit of the Earth is a perfect circle, in fact, it is an ellipse, therefore having some variation of equivalent distance from the Sun.
• At any rate, the orbital eccentricity is normally said not to have much effect on the seasons, although recent studies pointed out that it plays an important part.
• Changes of distance from the Sun happen to be important reason why Earth receives more or less solar energy, which affect the difference of temperature of seasons.

The Pacific Cold tongue and El Niño

• A recent study of the Pacific Cold Tongue (cooler part in the North Equatorial Pacific) indicates that orbital eccentricity has a large effect on the seasonal cycle of these phenomena.
• The above ocean atmosphere coupled phenomena are associated with the El Niño Southern Oscillation (ENSO), an influential climate activity regulating global weather patterns.
• During El Niño, the Pacific Cold Tongue becomes as much as 5°C warmer, and this causes alterations in global climate, such as droughts in India.

Effects on Monsoons

• Past orbital positions of the Earth have controlled the intensity of monsoons.
• Eleven thousand years ago, the Earth would orbit closest to the Sun when it was summer in the Northern Hemisphere, resulting in hot summers, cold winters, and stronger monsoons.
• However, now it is winter in the Northern Hemisphere, and the Earth is closest to the Sun, leading to relatively mild seasonal differences.

Other Planets and Seasonal Changes

• Other planets, like Mars, also have their seasons owing to their axial tilt.
• Mars has a similar axial tilt as that of the Earth, however, it does not have oceans and substantial greenhouse gases, making it much colder than the Earth.

Thus, axial tilt is the most important factor in maintaining the seasonal cycle on Earth, whereas newer studies suggest the importance of the other aspects such as orbital eccentricity. All these points are good for analyzing past climatic variations, as well as forecasting the coming weather trends.

Source: Times of India