“Our research goes to show that there are still a lot of surprises in the climate system,” said Seeley. across several days.Īfter the storm, the clouds dissipate, and precipitation stops for several days as the atmospheric battery recharges and the cycle continues. In one simulation, the researchers observed more rainfall in a six-hour period than some tropical cyclones drop in the U.S. After several days, the evaporative cooling from the upper atmosphere’s rainstorms erodes the barrier, triggering an hours-long deluge. If something can break through that barrier and allow the surface heat and humidity to break into the cool upper atmosphere, it’s going to cause an enormous rainstorm.” “You have a ton of cooling high in the atmosphere and a ton of evaporation and heating near the surface, separated by this barrier. “It’s like charging a massive battery,” said Seeley. The rain produced in those upper-level clouds evaporates before reaching the surface, returning all that water to the system. Instead, all that evaporation gets stuck in the near-surface atmosphere.Īt the same time, clouds form in the upper atmosphere, above the inhibition layer, as heat is lost to space. When the air near the surface becomes extremely warm, absorption of sunlight by atmospheric water vapor heats the air above the surface and forms what’s known as an “inhibition layer”, a barrier that prevents convective clouds from rising into the upper atmosphere and forming rain clouds. In an atmospheric model, Seeley and Wordsworth cranked up Earth’s sea surface temperature to a scalding 130 degrees Fahrenheit, either by adding more CO2 - about 64-times the amount currently in the atmosphere - or by increasing the brightness of the sun by about 10 percent.Īt those temperatures, surprising things start happening in the atmosphere. The research not only sheds light on Earth’s distant past and far-flung future but may also help to understand the climates of exoplanets orbiting distant stars. “This episodic cycle of deluges is a new and completely unexpected atmospheric state” said Robin Wordsworth, the Gordon McKay Professor of Environmental Science and Engineering at SEAS and senior author of the study. Then it would be quiet for a couple of days and repeat.” Then, suddenly, a massive rainstorm would erupt over almost the entire domain, dumping a tremendous amount of rain. “But we found that in extremely warm climates, there could be multiple days with no rain anywhere over a huge part of the ocean. Paulson School of Engineering and Applied Sciences (SEAS) and the Department of Earth and Planetary Science at Harvard and first author of the paper. “If you were to look at a large patch of the deep tropics today, it’s always raining somewhere,” said Jacob Seeley, a Postdoctoral Fellow in Environmental Science and Engineering at the Harvard John A. In a new study, researchers from Harvard University found that during these epochs of extreme heat, Earth may have experienced cycles of dryness followed by massive rainstorms hundreds of miles wide that could dump more than a foot of rain in a matter of hours. Little is known about how the atmosphere and climate behaved during these so-called hothouse periods. Earth likely experienced these temperatures at various times in the distant past and will experience them again hundreds of millions of years from now as the sun continues to brighten. Now, imagine an Earth 20 to 30 degrees Fahrenheit hotter than today. Today, we are experiencing the dramatic impacts that even a small increase in global temperatures can have on a planet’s climate.
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