Wind

When tropical meteorologists peer at satellite images, they often catch sight of subtle cloud formations hinting at something more ominous brewing. The first signs of a potential hurricane can be detected days before a storm gains its fierce momentum. Wispy cirrus clouds radiating outward, the appearance of curved banding low-level clouds and a drop in atmospheric pressure are all clues. These early clues are crucial for predicting the onset of what might develop into a catastrophic hurricane. I am a meteorology professor at Penn State, and my research group uses satellites and computer models to improve forecasting of tropical weather systems. With an especially fierce Atlantic storm season forecast for 2024, being able to detect these initial signals and provide early warnings is more important than ever. Here’s what forecasters look for. Hurricane Harvey entered the Gulf of Mexico as a tropical wave before reorganizing into a tropical storm a...

Spring 2024 was unnerving for people across large parts of the U.S. as tornado warnings and sirens sent them scrambling for safety. More than 1,100 tornadoes were reported through May − a preliminary number but nearly twice the 30-year average at that point and behind only 2011, when deadly tornado outbreaks tore across the southeastern U.S. The U.S. experienced several multistate outbreaks in 2024. Tornadoes damaged homes from Texas to Minnesota and east to West Virginia and Georgia. They caused widespread destruction in several towns, including Greenfield, Iowa; Westmoreland, Kansas; and Bartlesville, Oklahoma. Barnsdall, Oklahoma, was hit twice in two months. In May, at least one tornado occurred somewhere in the country almost every day. Greenfield, Iowa, after a powerful EF4 tornado cut through the city on May 21, 2024, amid a deadly tornado outbreak. What causes some years to have so many tornadoes? I’m a meteorologist w...

Weather forecasters talk about wind shear a lot during hurricane season, but what exactly is it? I teach meteorology at Georgia Tech, in a part of the country that pays close attention to the Atlantic hurricane season. Here’s a quick look at one of the key forces that can determine whether a storm will become a destructive hurricane. What is wind shear? Wind shear is defined as the change in wind speed, wind direction, or both, over some distance. You may have heard airplane pilots talk about turbulence and warn passengers that they’re in for a bumpy ride. They’re typically seeing signs of sudden changes in wind speed or wind direction directly ahead, and wind shear can sometimes cause this. With hurricanes, the focus is usually on vertical wind shear, or how wind changes in speed and direction with height. The effects of wind shear when wind speed increases with height (left) or changes direction (right)....

Strong winds spread the largest wildfire in Texas history across more than 1 million acres of rangeland in the Panhandle, the heart of the state’s cattle-producing region, and into Oklahoma in late February 2024. Light precipitation on Feb. 29 helped firefighters as they tried to contain the Smokehouse Creek Fire and other blazes threatening homes and livestock, but the heat and winds picked up again on March 2. At least two people died and scores of structures, including homes, burned. Karen Hickman, a grassland ecologist at Oklahoma State University and president of the Society for Range Management, explained why the fires spread so fast, the risks to livestock and how quickly these ecosystems can recover. How did the fires spread so far so quickly? This region of Texas and Oklahoma is mostly rangeland where cattle graze. A combination of higher-than-average temperatures and low humidity had dried out the dormant plants. When the winds picked up following a couple of ho...

Humans have contended with dust storms for thousands of years, ever since early civilizations appeared in the Middle East and North Africa. But modern desert dust storms are different from their preindustrial counterparts. Around the world, deserts now increasingly border built structures, including urban dwellings, manufacturing, transportation hubs, sewage treatment and landfills. As a result, desert dust lifts a growing load of airborne pollutants and transports these substances over long distances. This is happening throughout the Global Dust Belt, an arid to semiarid region that stretches from western China through Central Asia, the Middle East and North Africa. Similar storms occur in the U.S. Southwest and central Australia. Global pattern of dust frequency estimated from weather records, 1974-2012. Shao et al., 2013, CC BY-ND To our thinking, modern desert dust storms have been overlooked...