Why isn't the Winter Solstice the coldest day of the year?
The winter solstice (December 21)marked by the shortest day and longest night of the year, is intuitively perceived as being the coldest. However, meteorological observations reveal that the lowest temperatures usually occur about a month later. This discrepancy is intriguing and deserves a clear explanation based on the physical and environmental principles that govern our planet.
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December 21 is unexpectedly not the coldest day of the year
The axis of the Earththis imaginary line that passes through the North and South Poles, is tilted approximately 23.4 degrees relative to its orbit around the sun. This inclination is why we experience the seasons. During the winter solstice in the northern hemisphere, which occurs around December 21, the hemisphere is tilted away from the sun, reducing its exposure to solar rays. However, this reduction in sunlight does not immediately result in colder temperatures.
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The concept of seasonal delay
The delay between the solstice and extreme temperatures is explained by the phenomenon of “seasonal delay”. Oceans, lakes, soil and even urban construction like concrete accumulate and retain absorbed heat during warmer months. This thermal retention capacity means that the temperature of these masses does not drop immediately with decreasing solar exposure. Thus, the air cools more quickly than these large masses, which continue to slowly release the accumulated heat.
The influence of large bodies of water
The proximity of the oceans also modifies seasonal temperature variations. Water requires much more energy to heat or cool compared to materials like rock. Additionally, ocean circulation helps redistribute heat over large areas, mitigating extreme temperature variations near coasts and in adjacent regions. This may explain why places like the Pacific coast of the United States experience relatively milder winters and a greater delay between the solstice and their coldest period.
Global impacts
This shift between the solstice and the coldest or hottest periods of the year is not just an anecdote worth mentioning, since it has important practical implications for agriculture, resource management natural resources, and preparation for extreme weather events. Understanding this phenomenon helps humans plan better and anticipate better seasonal climatic variations.
Bubbles discovered in Antarctic ice prove scientists wrong about global warming
This article explores why the day with the least sunlight, the winter solstice, is not necessarily the coldest of the year. The explanation lies in the thermal properties of the Earth and the heat retention mechanisms of the oceans and land surfaces, illustrating the complexity of our planet's climate systems.
Source : wtamu.edu
