A new type of weather condition has been observed in one part of the world, and it's called compact, slow- moving pools. These are called 'atmospheric lakes' by researchers.
This type of storm occurs over the western Indian Ocean and moves towards Africa. Unlike most storms, the lakes are created by water vapor concentrations that are dense enough to produce rain.
These lakes are similar to atmospheric rivers. The new type of meteorological phenomenon is smaller, slower moving, and detaches itself from the weather system that creates it.
The lakes break away from other systems. Brian Mapes is the data set's author.
An abstract on the research presented at the Fall Meeting of the American Geophysical Union states that the rain can sometimes come from the west over the east African coast.
"These disconnected and drifting water bodies are called 'atmospheric lakes' because they are contiguous from source to coastline at an instant."
The atmospheric lakes are in no rush, like they are in an equatorial region where the wind speed is often very low. The longest storm to stay in the air for 27 days was found in an analysis of five years of meteorological data.
17 atmospheric lakes lasting longer than six days were discovered within 10 degrees of the equator over the five years. It seems that these lakes can happen in other regions as well.
A full study on the phenomenon is being put together. One of the questions the researchers will be looking at is why atmospheric lakes detach themselves from the river-lake patterns they form from, it's possibly due to the overall atmospheric wind patterns, or perhaps due to self-propelled winds produced internally.
"The winds that carry these things to shore are so close to zero that everything could affect them," says one of the researchers, atmospheric scientist Brian Mapes from the University of Miami.
"That's when you need to know, do they self- propel, or are they driven by some very much larger-scale wind patterns that may change with climate change?"
The climate change angle is important because it could affect the formation and movement of atmospheric lakes, which could impact the east coast of Africa, where it is sorely needed.
If all the water in a year's worth of atmospheric lakes were to be liquified at once, it would create a puddle just a few centimeters deep but a kilometer wide. That's a lot of precipitation.
The next step is to gather more data. It's a part of the world where rain and water vapor tend to be studied month-to-month rather than day-to-day, which may be why these lakes have been missed until this point.
"It's a place that's dry on average, so when these atmospheric lakes happen, they're surely very consequential," says Mapes.
I look forward to learning more about them in this area, where sailors used to call the monsoon for wind patterns, and have seen occasional rainstorms.
The research was presented at a meeting.
