Latest news with #atmosphericScientist
Yahoo
6 days ago
- Climate
- Yahoo
How does hail grow to the size of golf balls and even grapefruit? The science behind this destructive weather phenomenon
Hail the size of grapefruit shattered car windows in Johnson City, Texas. In June, 2024, a storm chaser found a hailstone almost as big as a pineapple. Even larger hailstones have been documented in South Dakota, Kansas and Nebraska. Hail has damaged airplanes and even crashed through the roofs of houses. How do hailstones get so large, and are hailstorms getting worse? As an atmospheric scientist, I study and teach about extreme weather and its risks. Here's how hail forms, how hailstorms may be changing, and some tips for staying safe. Hail begins as tiny crystals of ice that are swept into a thunderstorm's updraft. As these ice embryos collide with supercooled water – liquid water that has a temperature below freezing – the water freezes around each embryo, causing the embryo to grow. Supercooled water freezes at different rates, depending on the temperature of the hailstone surface, leaving layers of clear or cloudy ice as the hailstone moves around inside a thunderstorm. If you cut open a large hailstone, you can see those layers, similar to tree rings. The path a hailstone takes through a thunderstorm cloud, and the time it spends collecting supercooled water, dictates how large it can grow. Rotating, long-lived, severe thunderstorms called supercells tend to produce the largest hail. In supercells, hailstones can be suspended for 10-15 minutes or more in strong thunderstorm updrafts, where there is ample supercooled water, before falling out of the storm due to their weight or moving out of the updraft. Hail is most common during spring and summer when a few key ingredients are present: warm, humid air near the surface; an unstable air mass in the middle troposphere; winds strongly changing with height; and thunderstorms triggered by a weather system. Hailstorms can be destructive, particularly for farms, where barrages of even small hail can beat down crops and damage fruit. As hailstones get larger, their energy and force when they strike objects increases dramatically. Baseball-sized hail falling from the sky has as much kinetic energy as a typical major league fastball. As a result, property damage – such as to roofs, siding, windows and cars – increases as hail gets larger than the size of a quarter. Insured losses from severe weather, which are dominated by hail damage, have increased substantially over the past few decades. These increases have been driven mostly by growing populations in hail-prone areas, resulting in more property that can be damaged and the increasing costs to repair or replace property damaged by hail. A lot of people ask whether the rise in hail damage is tied to climate change. My colleagues and I analyzed four decades of hail environments and found that the atmospheric ingredients to produce very large hail – larger than golf balls – have become more common in parts of the central and eastern U.S. since 1979. Other studies that considered formation factors of hail-producing storms or looked at radar estimates of hail have found limited increases in large hail, predominately over the northern Plains. There are a couple of primary hypotheses as to why climate change may be making some key ingredients for large hail more common. First, there has been an increase in warm, humid air as the Earth warms. This supplies more energy to thunderstorms and makes supercooled water more plentiful in thunderstorms for hail to grow. Second, there have been more unstable air masses, originating over the higher terrain of western North America, that then move eastward. As snowpack disappears earlier in the year, these unstable air masses are more apt to form as the Sun heats up the land faster, similar to turning up a kitchen stove, which then heats up the atmosphere above. Climate change may also lead to less small hail and more large hail. As the atmosphere warms, the freezing level moves up higher in the atmosphere. Small hail would be able to melt completely before reaching the ground. Larger hail, on the other hand, falls faster and requires more time to melt, so it would be less affected by higher freezing levels. Additionally, the combination of more favorable ingredients for large hail and changes in the character of hailstorms themselves might lead to an increase in very large hail in the future. Being caught in a severe thunderstorm with large hail falling all around you can be frightening. Here are some safety tips if you ever wind up in such a situation: If you're driving, pull over safely. Stay in the vehicle. If you spot a garage or gas station awning that you can seek shelter under, drive to it. If you're outside, seek a sturdy shelter such as a building. If you're caught out in the open, protect your head. If you're inside, stay away from windows and remain inside until the hail stops. Dealing with the aftermath of hail damage can also be stressful, so taking some steps now can avoid headaches later. Know what your homeowners and car insurance policies cover. Be aware of roof replacement scams from people after a hailstorm. Also, think preventively by choosing building materials that can better withstand hail damage in the first place. This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Brian Tang, University at Albany, State University of New York Read more: Extreme heat waves aren't 'just summer': How climate change is heating up the weather, and what we can do about it What causes lightning and how to stay safe when you're caught in a storm – a meteorologist explains Why insurance companies are pulling out of California and Florida, and how to fix some of the underlying problems Brian Tang has received funding from the National Oceanic and Atmospheric Administration and Risk Prediction Initiative.
Fast Company
28-05-2025
- Climate
- Fast Company
Tornado Alley is shifting east. Here's what to know
Violent tornado outbreaks, like the storms that tore through parts of St. Louis and London, Kentucky, on May 16, have made 2025 seem like an especially active, deadly and destructive year for tornadoes. The U.S. has had more reported tornadoes than normal—more than 960 as of May 22, according to the National Weather Service's preliminary count. That's well above the national average of around 660 tornadoes reported by that point over the past 15 years, and it's similar to 2024—the second-most-active year over that same period. I'm an atmospheric scientist who studies natural hazards. What stands out about 2025 so far isn't just the number of tornadoes, but how Tornado Alley has encompassed just about everything east of the Rockies, and how tornado season is becoming all year. Why has 2025 been so active? The high tornado count in 2025 has a lot to do with the weather in March, which broke records with 299 reported tornadoes —far exceeding the average of 80 for that month over the past three decades. March's numbers were driven by two large tornado outbreaks: About 115 tornadoes swept across more than a dozen states March 14 to 16, stretching from Arkansas to Pennsylvania; and 145 tornadoes hit March 31 to April 1, primarily in a swath from Arkansas to Iowa and eastward. The 2025 numbers are preliminary pending final analyses. While meteorologists don't know for sure why March was so active, there were a couple of ingredients that favor tornadoes: First, in March the climate was in a weak La Niña pattern, which is associated with a wavier and stormier jet stream and, often, with more U.S. tornadoes. Second, the waters of the Gulf were much warmer than normal, which feeds moister air inland to fuel severe thunderstorms. By April and May, however, those ingredients had faded. The weak La Niña ended and the Gulf waters were closer to normal. April and May also produced tornado outbreaks, but the preliminary count over most of this period, since the March 31 to April 1 outbreak, has actually been close to the average, though things could still change. What has stood out in April and May is persistence: The jet stream has remained wavy, bringing with it the normal ebb and flow of stormy low-pressure weather systems mixed with sunny high-pressure systems. In May alone, tornadoes were reported in Colorado, Minnesota, Delaware, Florida, and just about every state in between. Years with fewer tornadoes often have calm periods of a couple of weeks or longer when a sunny high-pressure system is parked over the central U.S. However, the U.S. didn't really get one of those calm periods in spring 2025. Tornado Alley shifts eastward The locations of these storms have also been notable: The 2025 tornadoes through May have been widespread but clustered near the lower and central Mississippi Valley, stretching from Illinois to Mississippi. That's well to the east of traditional Tornado Alley, typically seen as stretching from Texas through Nebraska, and farther east than normal. April through May is still peak season for the Mississippi Valley, though it is usually on the eastern edge of activity rather than at the epicenter. The normal seasonal cycle of tornadoes moves inland from near the Gulf Coast in winter to the upper Midwest and Great Plains by summer. Over the past few decades, the U.S. has seen a broad shift in tornadoes in three ways: to the east, earlier in the year, and clustered into larger outbreaks. Winter tornadoes have become more frequent over the eastern U.S., from the southeast, dubbed Dixie Alley for its tornado activity in recent years, to the Midwest, particularly Kentucky, Illinois, and Indiana. Meanwhile, there has been a steady and stark decline in tornadoes in the 'traditional' tornado season and region: spring and summer in general, especially across the Great Plains. It may come as a surprise that the U.S. has actually seen a decrease in overall U.S. tornado activity over the past several decades, especially for intense tornadoes categorized as EF2 and above. There have been fewer days with a tornado. However, those tornado days have been producing more tornadoes. These trends may have stabilized over the past decade. Deadlier tornadoes This eastward shift is likely making tornadoes deadlier. Tornadoes in the Southeastern U.S. are more likely to strike overnight, when people are asleep and cannot quickly protect themselves, which makes these events dramatically more dangerous. The tornado that hit London, Kentucky, struck after 11 p.m. Many of the victims were older than 65. The shift toward more winter tornadoes has also left people more vulnerable. Since they may not expect tornadoes at that time of year, they are likely to be less prepared. Tornado detection and forecasting is rapidly improving and has saved thousands of lives over the past 50-plus years, but forecasts can save lives only if people are able to receive them. This shift in tornadoes to the east and earlier in the year is very similar to how scientists expect severe thunderstorms to change as the world warms. However, researchers don't know whether the overall downward trend in tornadoes is driven by warming or will continue into the future. Field campaigns studying how tornadoes form may help us better answer this question. Remember that it only takes one For safety, it's time to stop focusing on spring as tornado season and the Great Plains as Tornado Alley. Tornado Alley is really all of the U.S. east of the Rockies and west of the Appalachians for most of the year. The farther south you live, the longer your tornado season lasts. Forecasters say it every year for hurricanes, and we badly need to start saying it for tornadoes too: It only takes one to make it a bad season for you or your community. Just ask the residents of London, Kentucky; St. Louis; Plevna and Grinnell, Kansas; and McNairy County, Tennessee. if you hear sirens or are under a tornado warning, immediately go to your safe space. A tornado may already be on the ground, and you may have only seconds to protect yourself.
