(ORDO NEWS) — NASA‘s Apollo program explored the Moon, but it also helped us explore the Earth by providing some of the first high-resolution images of our planet.
Scientists expected that the two hemispheres of the Earth, northern and southern, would have a difference in albedo (the amount of light they reflect).
This is because the northern and southern hemispheres of the Earth are very different from each other.
The southern hemisphere is mostly covered in dark oceans, while the northern hemisphere contains vast landmasses that are much brighter than the oceans.
However, when the Earth is viewed from space, both hemispheres appear equally bright.
This brightness symmetry has been a mystery for over 50 years. But now a new study shows that the albedo is about the same due to increased cloudiness and storms in the southern hemisphere.
“The cloud albedo resulting from severe storms over the Southern Hemisphere has been found to be a highly accurate compensating factor for the large land area in the Northern Hemisphere, and thus the symmetry is maintained,” said Ohr Hadas of the Weizmann Institute of Science in Canada.
“This suggests that storms are the connecting factor between the brightness of the Earth’s surface and the brightness of clouds, solving the puzzle of symmetry.”
Hadas and co-author Yochai Kaspi analyzed the data, which included cloud data collected by NASA’s CERES program.
They also used data from ERA5, which is a global weather database containing information collected from various sources, both from the air and on the ground, dating back to 1950.
Based on this data, they used cloud data to cross-correlate with information on the intensity of cyclones and anticyclones.
They found a direct relationship between the intensity of a storm and the amount of clouds that form around the storm.
The northern hemisphere generally has weaker storms over the oceans, while the southern hemisphere has experienced severe to moderate storms.
An analysis of their data showed that the relationship between storm intensity explained the difference in cloud cover between the two hemispheres, even though the northern hemisphere’s land area is about twice that of the southern hemisphere’s.
Therefore, increased cloudiness in the southern hemisphere explains the similarity in albedo.
In addition, the team’s study provided an assessment of how climate change could change the rate of reflection in the future.
Models predict that global warming will change the frequency of storms in both the north and south, and some have suggested that we might one day be able to detect a discontinuity in reflectivity between the two hemispheres.
But this study shows a lot of uncertainty in this line of thinking.
“It is not yet possible to determine with certainty whether the symmetry will break in the face of global warming,” Kaspi said.
“As global warming continues, geoengineering solutions will become vital to the continuation of human life.
I hope that a better understanding of basic climatic phenomena, such as hemispheric albedo symmetry, will help in developing these solutions.”
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