There are billions of gallons of water, mostly in the form of steam, in the sky right now, and if it all fell at once it would cause some major problems for millions of people.
Earth is often called the “blue planet” because of the abundance of water on it unlike other planets, both inside and outside the solar system.
About 71% of the Earth’s surface is covered by water, and this abundance of liquid water on the planet has allowed millions of species to evolve and thrive.
According to the US Geological Survey (USGS), 96.5% of the planet’s water supply is in the oceans, but the water doesn’t just stay below; It ascends into the atmosphere as well, as part of the water cycle, also called the hydrological cycle.
But how much water is in the atmosphere? How much water is over our heads now, and if it all fell at once, what effect would it have?
How is the water above us in the first place?
As stated in an article on the Live Science website, there are billions of gallons of water, mostly in the form of vapor, present in the sky now, and if it all fell at once, it would cause some major problems for millions of people.
According to the US Geological Survey, the volume of all water on Earth is estimated at 1.4 billion cubic kilometres.
As a result of the hydrologic cycle, which is one of the major biogeochemical cycles, the Earth’s water does not remain in one place for a long time. Water moves between the oceans, the Earth’s surface, and the atmosphere.
Every day the water evaporates from the seas and is carried in the air and condenses to form clouds, and then returns to the land in the form of precipitation, and finally returns from the land to the sea through the rivers, thus completing the cycle.
What if all the water fell over our heads?
According to the British Encyclopedia Britannica, the evaporated water stays in the atmosphere for 10 days, meaning that the atmosphere is actually immersed in water vapor.
“On average, there is the equivalent of approximately 30 mm of rain in the form of vapor available to fall on any point on the Earth’s surface,” Frederic Fabri, associate professor of environment and department of atmospheric and ocean sciences at McGill University in Canada, says in an email to Live Science. “. “This represents about 25 kilograms of water per square yard (0.9144 metres), and most of it is in the form of steam.”
Fabry adds that given that the Earth’s surface area is about 510 million square kilometers, there is more than about 170 million liters of water in the atmosphere.
He added that if all this mass fell at once, it would raise the level of the global ocean by about 3.8 cm.
Although all this steam falling at once is highly unlikely, such a dramatic rise in sea level is likely to have disastrous consequences.
According to Climate Change Post, if the global sea level rises by just 5 cm, then low-lying cities, such as Mumbai and Kochi in India; Abidjan, Ivory Coast; Jakarta in Indonesia, which has a combined population of more than 28 million and is already prone to coastal flooding, will be “significantly affected”.
Additionally, according to a 2017 study published in Scientific Reports, if sea levels rise between 5 and 10 cm, flooding will double in a range of regions, especially in the tropics.
Water does not fall evenly
If all the water in the atmosphere falls spontaneously in some way, it will not fall evenly around the world, because some regions of the Earth are wetter than others.
“The amount of water in the atmosphere is controlled by the balance between the inflow and outflow from the atmosphere,” Fabry says.
The flow in the atmosphere is controlled by evaporation from the surface, and this depends on whether there is water on the surface, as well as on the temperature. The evaporation of water requires a lot of energy, and this energy comes from the warmth of the surface. The warm ocean is where where evaporation is the greatest, while the land areas in the Arctic are the least.
The average amount of water in the atmosphere varies with season and location, but in general, “tropical oceans and humid tropics contain the most water vapor above them, and these move with seasons; land areas in the Arctic or high mountain regions are least,” because the warm air Much better for carrying water.”
Geology and topography are other influencing factors, such as the sloping terrain, which affects how quickly air moves up into the atmosphere, as it cools.
As a result, Fabri says, the mountainous regions “get more than their share of rain”. This partly explains why there was so much rain in Seattle, a city near the Cascade Range, according to the US Geological Survey.
It is worth noting that climate change may affect the amount of vapor in the atmosphere in the coming decades.
“If temperatures rise, evaporation from the surface will increase, and so will the amount of water in the atmosphere,” Fabry says.
As a result, the acceleration of global warming can be visualized. Water vapor is a very effective greenhouse gas, and when more of it is in the atmosphere, it contributes to warming the water and enhancing the greenhouse effect.