Arabia Weather - Atmospheric rivers - Sky rivers - They are an important part of the Earth's climate, as they are responsible for 90% of the movement of moisture from the tropical regions towards the poles.
Atmospheric rivers: They are long, narrow sections of the Earth's atmosphere that carry high amounts of moisture, and extend over a range of tens to hundreds of kilometers, through which moisture is transported from the Earth's tropical regions near the equator towards the poles. Because of these characteristics, they look like rivers flowing in the sky.
On average, Earth has 4 to 5 active weather rivers in the atmosphere at any given time. When atmospheric rivers reach land, their moisture content is released in the form of rain or snow.
Atmospheric rivers vary greatly in size and strength. While a temperate atmospheric river carries an amount of water vapor roughly equivalent to the average water flow at the mouth of the Mississippi River, exceptionally strong atmospheric rivers can transport up to 15 times that amount.
For any river to form in the atmosphere, three factors must be present together:
The main factors that contribute to the formation of atmospheric rivers include the presence of strong low-level winds that act as a rapid means of transporting water vapor through the atmosphere. These conditions are achieved thanks to the jet streams found in the northern and southern hemispheres, where wind speeds reach 442 km/h ( 275 mph).
Then comes the need for high levels of humidity in the atmosphere , as this contributes to supplying atmospheric rivers with the moisture necessary for cloud formation and precipitation.
Finally, the presence of rising terrain such as mountain ranges is an important factor, as it helps transport air masses from low-altitude areas to higher altitudes, which contributes to quickly cooling the air and increasing the humidity in it, and thus contributes to the formation of clouds and precipitation or snow in the appropriate places.
In general, sky rivers form during the winter, i.e. during December, January and February in the Northern Hemisphere. During this period, weather conditions are suitable for the formation of dense clouds, rain and snow.
While sky rivers are formed in the southern hemisphere during the northern winter, that is, during June, July, and August. During this period, climatic conditions in the southern hemisphere are favorable for cloud formation and rainfall, as a result of the temperature contrast between the polar regions and the tropics.
Atmospheric rivers are a vital part of the Earth's climate, as they play an important role in transporting moisture from the tropics towards the poles, and forming clouds. Atmospheric rivers transport about 90% of moisture movement through the atmosphere, making them a major factor in cloud formation and determining air temperatures and environmental systems.
The ecosystem is greatly influenced by atmospheric rivers, as organisms depend on moisture and rain to grow and reproduce. In addition, temperatures affect the distribution of plants and animals, and thus atmospheric rivers directly affect ecosystem balance.
As an essential part of the ecosystem, understanding atmospheric rivers and their impact on the environment and climate is vital to keeping the planet balanced and sustainable.
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Research indicates that sky rivers play a vital role in the climate system and environment, being responsible for more than half of the precipitation in many regions, such as the coasts of North America, France, Spain, Portugal, the United Kingdom, South America, Southeast Asia and New Zealand. It also contributes to the formation of snow storms that increase snow accumulation in a balanced manner.
In addition, sky rivers play an important role in increasing water levels in watersheds, enhancing ecosystem biodiversity. It contributes to replenishing groundwater reserves, as fresh water is stored in snow accumulations during the cold months and then melts during the warm months, replenishing the watersheds and returning the water to its natural levels.
In addition, snow's ability to reflect sunlight and heat back into the atmosphere helps cool the Earth's surface, playing an important role in regulating local temperatures and climate.
From another angle, the importance of atmospheric rivers is highlighted in redistributing fresh water supplies across the planet in a balanced manner, as these rivers transport moisture over long distances, which helps provide fresh water in different regions.
Most of the world's fresh water is associated with glaciers, with only fresh surface water accounting for a small percentage of total fresh water. Although rivers make up a very small percentage of this surface water, they are the primary source of water for humanity.
Sky rivers therefore play a vital role in maintaining water security for local communities, providing water for drinking, agriculture and industry. Thanks to their ability to transport moisture and supply water to dry areas, atmospheric rivers are an essential part of the ecological and economic balance.
Climate change significantly affects the timing and distribution of atmospheric rivers, which could lead to a redistribution of global water supplies. Rising global temperatures increase the moisture content in the air, leading to an increase in the frequency and intensity of sky rivers and rainfall in general.
Simulation programs and tools used to study sky rivers underestimate their intensity by up to 50%, which is what prompted Chinese researchers from China's Ocean University to use accurate simulation methods with an error of only 10%. They published the results of their study in the journal "The Nature" last summer, where they indicated that the amounts of water vapor and precipitation associated with sky rivers may more than double, and the number of sky rivers descending to land may reach record levels by up to three times as much by the end of this century.
A study published last month confirms the seriousness of these changes, as the researchers aimed to study the change in the spread of atmospheric rivers since 1988 and predict how this change will continue until 2099.
The study concluded that sky rivers will increase by 84% between December and February, and by 113% between June and August, at the global level, in light of the continued significant use of fossil fuels. For average greenhouse gas emissions, increases of 34% and 46% are expected in the same time periods. Expectations indicate that the northern Indian Ocean will witness the largest increase in the frequency of atmospheric rivers, which may reach a three-fold increase.
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A warmer climate raises concerns about winter precipitation turning to rain instead of snow, as well as an increase in extreme precipitation during the winter. These shifts increase the possibility of flooding in areas that are not accustomed to such large amounts of rain. The state of California in the United States showed a horrific example of this last month and the beginning of this month, as atmospheric rivers caused heavy rains and massive floods in a short time.
Therefore, it is of great importance to understand how the frequency and intensity of atmospheric rivers increase with climate change, in order to improve planning for maintaining local water security and forecasting storms and floods. We must enhance preparedness and adopt preventive measures to limit the damage that these phenomena can cause to infrastructure and the safety of the public in general.
Source: aljazeera
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