Due to the tilt and rotation of the Earth, our planet experiences global weather patterns, which vary in different locations. They are divided into six climate zones based on the categories proposed by German climatologist and amateur botanist Wladimir Köppen. While other parts of the Earth experience different intensities of heat, the North and South Poles are consistently colder than the rest of the world.
Why are the Poles so Cold?
The Earth's polar regions are cold because their positions at the top and bottom of the planet do not allow them to receive direct light from the Sun. Since the Earth's axis is tilted at 23.5 degrees, the incoming solar radiation that warms the planet strikes them obliquely rather than vertically. As a result, the poles receive only 40% as much incident radiation as equatorial regions.
In both poles, the Sun always rests low on the horizon, even during summer. During the winter, the Sun lies so far below the horizon that it does not come up for months. Without enough energy from the Sun to warm the poles, their surface temperatures remain low.
This factor is associated with the atmospheric length, affecting the polar climate. The rays of the Sun need to travel through the atmosphere to the Earth's surface. This distance is less when the Sun is directly overhead, like at the equator, than it is when the Sun is near the horizon. The longer the atmospheric length, the less solar radiation reaches the surface.
Reflection also contributes to the temperature of the poles. Ice, water, and snow are all good reflectors of solar radiation, especially when the Sun is near the horizon. The white surfaces of the ice and snow at the poles are highly reflective and act like mirrors. Most of the energy from the Sun bounces back into space after reaching the surface of the poles. Because of this, the air above those surfaces is relatively cool.
The presence of less water vapor in the poles is another contributing factor. Water vapor is one of the most significant greenhouse gases in the atmosphere, yet the poles do not hold water vapor as much as the tropical regions. Cold air has a low capacity to evaporate water; less moisture means more heat escapes into space.
The vast amounts of ice and snow also cool the air above the poles. The heavy, cold air sinks through the atmosphere, creating high-pressure areas with out-flowing winds moving toward the equator.
Arctic versus Antarctic
While all those factors make both poles chilly, the South Pole is significantly colder than the North Pole, according to the Woods Hole Oceanographic Institution. The annual average temperature at the North Pole is -40 degrees Fahrenheit (-40 degrees Celsius)in winter and 32 degrees Fahrenheit (0 degree Celsius) in summer. Meanwhile, the South Pole has an annual average temperature of -76 degrees Fahrenheit (-60 degrees Celsius) in winter and -18 degrees Fahrenheit (-28.2 degrees Celsius) in summer.
The main reason the South Pole is colder than the North is due to their key difference. The North Pole is an ocean surrounded by land, while the South Pole is land surrounded by water. Since water cools and warms more slowly than land, it results in fewer temperature extremes.
Aside from this, the Arctic lies at sea level, while Antarctica is the highest continent with an elevation of about 7,500 feet (2,300 meters). The higher the altitude gets, the colder a place becomes.
Check out more news and information on Poles in Science Times.
