For more than two decades, the Earth gradually became darker. Using 24 years of data from NASA clouds and the radiant energy system of the Earth (Ceres), the researchers learned that this invasion darkness is due to the fact that the Earth reflects less sunlight, while the most dramatic fell silent in the northern hemisphere.
Published in Proceedings of the National Academy of SciencesThis new study emphasizes the arising imbalance in the “radiation budget” of the planet. The radiation budget is a delicate balance between the sunlight, absorbs the earth, and the energy that it radiates into space.
Northern and southern hemispheres
On average, the northern and southern hemispheres receive approximately the same amount of solar energy that it means that they should also reflect the same amount. Nevertheless, the northern hemisphere currently absorbs more sunlight and radiates more sociable long -wave radiation (OLR) than its southern analogue.
According to the research group, this shift is that atmospheric and ocean currents can no longer fully compensate.
“The general increase in long -wave radiation cooling in both hemispheres is the result of deposits on the temperature and changes in the cloud, partially compensating for the contributions as a result of changes in the water steam and marks of gases,” the authors said in their article.
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Why does the earth become darker?
The key factor that underlies this global shade lies in the changes in the Albedo of the Earth. Albedo is a measure of how many sunlight the surface is reflected. Lighty areas, such as ice, snow and clouds, bounce off most of the sun’s energy back into space, while darker surfaces, such as forests, oceans and asphalt, absorb it. More reflections mean cooler temperatures, and more absorption means warmer temperatures.
The rapid darkening of the northern hemisphere can be traced to changes in his Albedo with a decrease in snow cover and Melting of sea ice In this area, it significantly reduces reflective ability.
In an even more unusual turn, cleaner air in the Northern Hemisphere negatively influenced his Albedo. For decades, industrial pollution scattered sunlight and helped to form bright, reflecting clouds. These tiny air particles, known as aerosols, once acted like natural mirrors, bouncing energy back into space.
Thanks to the more stringent laws on the quality of air throughout Europe, North America and China, the air is cleaner, but it also reflects less sunlight. With a smaller number of aerosols in the atmosphere, the planet absorbs more heat.
On the contrary, in the southern hemisphere, temporary bursts of reflective ability occurred. Large natural events, such as Australia Forest Fires and Civil The volcanic eruption periodically filled the sky with aerosols and the reflection of sunlight increased.
How else does dark land affect our future?
These new conclusions indicate a continuous possibility: earthly clouds, which are believed to automatically compensate for changes in radiation, may not be able to save us from Additional warmingThe field of many current climatic models work on the assumption that the clouds will behave in such expected ways and stabilize the energy balance of the planet. However, a new study involves a different one.
“Since the darkening (compared to the southern hemisphere) is not compensated by the clouds in the northern hemisphere (compared to the southern hemisphere), this suggests that there may be a limitation of the role of clouds in maintaining the symmetry of the hemisphere in Albedo,” the authors of the study say.
If this is true, the northern hemisphere can continue to heat up faster than the average in the world, and continue to see more intense and long summer in the coming years. To fight and prepare for this, the researchers suggest that climatic models may need to be repaired in order to reflect these changes in the decreasing role of clouds in providing assistance in the management of the Earth.
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