Experts in the News

The 2024 Atlantic hurricane season has been intense, marked by multiple powerful storms hitting the U.S. coast. The season runs from June 1 to November 30, with conditions like warm ocean temperatures and low wind shear fostering storm development. "Storms can intensify fast if they encounter the right conditions and that could happen at any time," says Annalisa Bracco, associate chair and professor in the School of Earth and Atmospheric Sciences. "But we are later in the season, and that means that favorable conditions for fast intensification are less likely than when Milton happened. Wind shear tends to be stronger — on average — at the end of October compared to early September, and sea surface temperatures are on average cooler than in August-September."

Talk about a Halloween treat. Astronomers say a recently discovered comet will be blazing by the Earth in broad daylight just in time for Halloween. Professor James Wray in the School of Earth and Atmospheric Sciences says Comet C/2024 S1, first found at the end of September, will pass around the Earth on Oct. 24. "Look low in the eastern sky just before sunrise,” says Wray. "Then, after swinging around the sun, the comet may reappear in the western night sky right around Halloween.”

Related Coverage: The Times of India, Space.com

Extreme weather linked to climate change drives people to rely on familiar but unreliable sources like the Farmers’ Almanac for forecasts, which are only about 52% accurate. In contrast, the National Weather Service (NWS) offers structured long-term forecasts focused on temperature and precipitation. Senior Academic Professional Zachary Handlos in the School of Earth and Atmospheric Sciences says both sources have the same general idea. "They have one or two writers that put out a winter forecast every year,” says Handlos. “I think they keep the identity of the writers a little cryptic. It’s part of the lore of reading it. Both claim that their forecasts are science based. But some of it’s also a mix of what farmers know in terms of intuition, astronomy and things like that. There's a little bit of folklore, which makes it fun.”

A potential tropical storm, which would be named Nadine, is forming in the central Atlantic with a low chance of developing into a hurricane. It’s expected to pass near the Virgin Islands, Puerto Rico, and the Bahamas, though strong winds may prevent further strengthening. Annalisa Bracco, professor in the School of Earth and Atmospheric Sciences, says very warm sea surface temperature — the engine in terms of energy for the storm to grow — along with low wind shear and low surface salinity, help storms intensify by concentrating the high temperatures near the surface. 

Two weeks ago, a facility owned by BioLab in Conyers, Georgia, outside of Atlanta blew up, sending a huge and rancid cloud miles around. It seems the water used to extinguish the fire reacted with pool chemicals in the plant, which made the cloud more noxious. Sally Ng, a professor in the School of Earth and Atmospheric Sciences, says a system known as the Atmospheric Science and Chemistry Measurement Network detected a 1,400-times increase in the amount of chlorine-containing particles in the air, and a 170-times increase in the amount of bromine-containing particles in the air over Decatur.

Through the weekend of Saturday, Oct. 19, and Sunday, Oct. 20, you'll be able to see a rare comet in the sky each evening above north Georgia. Comet C/2023 A3, known as Comet Tsuchinshan-ATLAS, will be visible about 30 minutes after sunset and can be seen in the western sky. James Wray, professor in the School of Earth and Atmospheric Sciences, discusses his research on the comet and the Oort Cloud.  "The human mind may find it difficult to conceptualize: a cosmic cloud so colossal it surrounds the Sun and eight planets as it extends trillions of miles into deep space," Wray says. "The spherical shell known as the Oort Cloud is, for all practical purposes, invisible."

The Oort Cloud is a theoretical, massive spherical shell surrounding the Sun and planets. Though invisible due to its vast size and faint particles, astronomers infer its existence as it explains the appearance of long-period comets. In The Conversation, James Wray,  professor in the School of Earth and Atmospheric Sciences, discusses his research on the Oort Cloud, along with two comets—Tsuchinshan-ATLAS (Comet C/2023 A3) and C/2024 S1 (ATLAS)—which are expected to be visible this month. 

Related Coverage: Ars Technica, Discover Magazine, The Current

NASA images of Hurricane Milton, showing unusually high sea surface temperatures, highlight how climate conditions can accelerate hurricane intensification. The Gulf of Mexico’s waters, particularly those above 89.6 degrees Fahrenheit, played a key role in the rapid development of Milton into a Category 5 storm.

"Numerical models in the past five years or so have improved to resolve hurricanes and typhoons at global scales and they do agree that the intensification of hurricanes - more hurricanes of strength 4 or 5 - and typhoons, and a tendency for depression to turn more easily into hurricanes is the result of climate change," says Annalisa Bracco, professor in the School of Earth and Atmospheric Sciences. 

Related Coverage: Cross Country

Category 5 is currently the highest hurricane category, but many experts suggest that as hurricanes become more powerful due to climate change, a Category 6 may be needed. "There is strong agreement that the frequency and intensity of major tropical cyclones — Category 3 and above — are likely to increase as a result of climate change," says Ali Sarhadi, assistant professor in the School of Earth and Atmospheric Sciences. "This is driven by rising ocean temperatures, which provide more thermal energy to fuel tropical cyclones, and the increased capacity of a warmer atmosphere to hold moisture, leading to heavier rainfall during the landfall of these storms." 

Hurricane Milton became one of the most rapidly intensifying storms on record as it went from barely hurricane strength to a dangerous Category 5 storm in less than a day on a path across the Gulf of Mexico toward Florida. In an article in The Conversation, Senior Academic Professional Zachary Handlos and Assistant Professor Ali Sarhadi, both in the School of Earth and Atmospheric Sciences, discuss their research on hurricane behavior, rapid intensification, and what causes rapid intensification. Rapid intensification is defined by the National Weather Service as an increase in a tropical cyclone’s maximum sustained wind speed of at least 30 knots – about 35 mph within a 24-hour period.

A BioLab manufacturing facility in Conyers is continuing to release chlorine, chloramines and chlorine compounds in an incident that originated from a small rooftop fire in the early morning of September 29. The fire activated a sprinkler system and doused water-reactive trichloroisocyanuric acid (TCCA) inside the building. This initiated a chemical decomposition reaction that released chlorine gas into the atmosphere. 

Love Family Professor Sally Ng in the School of Earth and Atmospheric Sciences confirms the morning after the fire, the number of chlorine-containing particles detected in the air at the Ascent's Decatur site, around 28km from the BioLab plant, had increased by about 1400 times. Bromine-containing particles in the air increases by about 170 times, she says. 

The freshly formed Tropical Storm Leslie is heading in the direction of the East Coast as it intensifies, current National Hurricane Center (NHC) forecasts predict. Low wind shear, as well as sea surface temperatures and atmospheric moisture, are key factors that affect whether a storm will intensify into a hurricane, and how strong that hurricane might get. Senior Academic Professional Zachary Handlos in the School of Earth and Atmospheric Sciences says "tropical cyclones primarily thrive from the following atmospheric ingredients: warm sea surface temperatures and a sufficiently deep layer of warm water, all serving as a key source of energy for a tropical cyclone as well as weak middle and upper level atmospheric winds."