The strongest geomagnetic storm in 20 years made the colorful northern lights, or aurora borealis, visible Friday night across the US, even in areas that are normally too far south to see them. And the show may not be over. Tonight may offer another chance to catch the aurora if you have clear skies, according to the NOAA, and Sunday could bring yet more displays reaching as far as Alabama.
The extreme geomagnetic storm continues and will persist through at least Sunday... pic.twitter.com/GMDKikl7mA
— NOAA Space Weather Prediction Center (@NWSSWPC) May 11, 2024
The NOAA’s Space Weather Prediction Center said on Saturday that the sun has continued to produce powerful solar flares. That’s on top of previously observed coronal mass ejections (CMEs), or explosions of magnetized plasma, that won’t reach Earth until tomorrow. The agency has been monitoring a particularly active sunspot cluster since Wednesday, and confirmed yesterday that it had observed G5 conditions — the level designated “extreme” — which haven’t been seen since October 2003. In a press release on Friday, Clinton Wallace, Director, NOAA’s Space Weather Prediction Center, said the current storm is “an unusual and potentially historic event.”
The Sun emitted two strong solar flares on May 10-11, 2024, peaking at 9:23 p.m. EDT on May 10, and 7:44 a.m. EDT on May 11. NASA’s Solar Dynamics Observatory captured images of the events, which were classified as X5.8 and X1.5-class flares. https://t.co/nLfnG1OvvEpic.twitter.com/LjmI0rk2Wm
Geomagnetic storms happen when outbursts from the sun interact with Earth’s magnetosphere. While it all has kind of a scary ring to it, people on the ground don’t really have anything to worry about. As NASA explained on X, “Harmful radiation from a flare cannot pass through Earth’s atmosphere” to physically affect us. These storms can mess with our technology, though, and have been known to disrupt communications, GPS, satellite operations and even the power grid.
This article originally appeared on Engadget at https://www.engadget.com/extreme-geomagnetic-storm-may-bless-us-with-more-aurora-displays-tonight-and-tomorrow-192033210.html?src=rss
Nothing is probably more unpredictable than weather, and temperatures can vary greatly even in the same season. People often prepare different wardrobes for different situations, but it can get pretty cumbersome to keep switching jackets whenever the weather changes. Plus, you might have a favorite that you wish you could use whether it’s chilly, sunny, or even rainy. The good news is that such a jacket is no longer just a dream but a toasty reality, thanks to an ingenious jacket design that not only lets you select your desired warmth but also lets you add or remove parts to match the weather, the season, and your sense of style.
Designer: Carolina Gutierrez, founder of UZE, a Miami-based start-up
One Jacket, Countless Options – Thanks to the precision engineering of its modular design, you get more than a jacket – you get an ally for every occasion.
Heated jackets have been around for quite a bit, but the majority of them are as effective as shoving a hot pack inside the jacket’s pocket. You only have one level of heat, which may be too little or too much depending on the weather. These jackets are also designed to be thick and bulky to keep your body warm, which means you can only use them for a limited number of months each year. The UZE Heated Jacket changes the game completely, promising a jacket that you can wear in all four seasons while giving you the power to decide just how toasty you really need to be.
Look Cool, Feel Hot – Four Graphene heat zones and three heat settings (120°F, 140°F, 160°F) ensure you stay warm in any weather.
The secret to this unbelievable feat is the same graphene technology that the brand uses for its popular power banks, which happens to be a remarkable material for heat conduction. With four graphene heat zones and three heat settings of 120°F, 140°F, and 160°F, you don’t have to frantically search for the right jacket just because it suddenly gets colder or warmer. With a simple touch of a button, you can select the level of warmth that will make you feel comfortable, whether you’re going out for a brisk morning walk or braving the snow. And you don’t have to worry about your jacket running out of power in the middle of the day. UZE is best known for its power banks, so you shouldn’t be surprised that its Heated Jacket carries one that can keep you warm for up to 10 hours and charges in 45 minutes, 10x faster than your run-of-the-mill heated jacket.
Charge 10x Faster, Instant Warmth – The UZE Power Bank keeps you warm for up to 10 hours and charges 10x faster than typical heated jacket power banks (45 minutes vs. 8 hours).
That adjustable warmth is just one of the UZE Heated Jacket’s superpowers. Even when you don’t actually need that kind of heat, the jacket provides comfort and style all year round thanks to its modular design and stylish looks. Add a fur-lined hood when you want to keep your head warm as well or remove the liner when you want a snug fit. There’s even an underarm zipper for better ventilation, perfect for people with more active lifestyles. So yes, you can even wear it as part of your summer glam or fall fashion with its clean style and modern looks.
No More Raining on Your Parade – The fabric’s membranes are 20,000 times smaller than a drop of water but larger than water vapor molecules, achieving superior breathability.
Everything In Its Place, Always Within Reach – Instant access, all within reach. Bank card, key card or ski pass. Bid farewell to fiddly pockets.
One Jacket, Countless Options – Thanks to the precision engineering of its modular design, you get more than a jacket – you get an ally for every occasion.
With waterproof zippers and the specially-developed UZEShield fabric, you can also wear it under the rain or in strong winds. This proprietary fabric prevents water droplets from getting in while allowing water vapor to escape, ensuring enhanced breathability. Want to travel light without a bag? The jacket has plenty of pockets to carry not just the power bank, but also your phone, cards, and other accessories. It even has a cloth wiper for your sunglasses and a built-in keychain holder so you won’t have to worry about losing your keys ever again. With the UZE Heated Jacket, you’re in complete control of your comfort and your style, giving you the exact amount of warmth and protection you need, regardless of what the weather throws at you.
A machine learning-based weather prediction program developed by DeepMind researchers called “GraphCast” can predict weather variables over the span of 10 days, in under one minute. In a report, scientists highlight that GraphCast has outperformed traditional weather pattern prediction technologies at a 90% verification rate.
The AI-powered weather prediction program works by taking in “the two most recent states of Earth’s weather,” which includes the variables from the time of the test and six hours prior. Using that data, GraphCast can predict what the state of the weather will be in six hours.
In practice, AI has already showcased its applicability in the real world. The tool predicted the landfall of Hurricane Lee in Long Island 10 days before it happened, while the traditional weather prediction technologies being used by meteorologists at the time lagged behind. Forecasts made by standard weather simulations can take longer because traditionally, models have to account for complicated physics and fluid dynamics to make accurate predictions.
Not only does the weather prediction algorithm outperform traditional technologies to forecast weather patterns in terms of pace and scale, GraphCast can also predict severe weather events, which includes tropical cyclones and waves of extreme temperatures over regions. And because the algorithm can be re-trained with recent data, scientists believe that the tool will only get better at predicting oscillations in weather patterns that coincide with grander changes that align with climate change.
Soon, GraphCast, or at least the basis of the AI algorithm that powers its predictions, might pop up into more mainstream services. According to Wired, Google might be exploring how to integrate GraphCast into its products. The call for better storm modeling has already paved a path for supercomputers in the space. The NOAA (National Oceanic and Atmospheric Administration) says it has been working to develop models that will provide more accurate readings on when severe weather events might occur and importantly, the intensity forecasts for hurricanes.
This article originally appeared on Engadget at https://www.engadget.com/ai-is-starting-to-outperform-meteorologists-173616631.html?src=rss
On Monday, meteorologists documented the hottest day in recorded history, according to US National Centers for Environmental Prediction (via Reuters). July 3rd, 2023 saw average global temperatures edge past 17-degrees Celsius (62.62 Fahrenheit) for the first time since satellite monitoring of global temperatures began in 1979. Scientists believe Monday is also the hottest day on record since humans began using instruments to measure daily temperatures in the late 19th century. The previous record was set in August 2016 when the world’s average temperature climbed to 16.92C (62.45 Fahrenheit).
This week, the southern US is sweltering under a heat dome that has sent local temperatures past the 110 Fahrenheit mark (43C). Even places that normally aren’t known for their warm weather have been unseasonably hot in recent days and weeks, with the Vernadsky Research Base in Antarctica recording a July high of 8.7C.
Scientists attribute the recent heat to a combination of El Niño and ongoing human-driven emissions of greenhouse gases. Studies have shown that climate change is contributing to heat waves that are more frequent, last longer and hotter than ever. "The average global surface air temperature reaching 17C for the first time since we have reliable records available is a significant symbolic milestone in our warming world," climate researcher Leon Simons told BBC News. "Now that the warmer phase of El Niño is starting we can expect a lot more daily, monthly and annual records breaking in the next 1.5 years.”
This article originally appeared on Engadget at https://www.engadget.com/july-3rd-was-the-hottest-day-in-recorded-history-214854746.html?src=rss
Amazon told lawmakers it wouldn’t build storm shelters in its warehouses after a December 2021 tornado killed six employees at an Illinois location. Although the company changed its severe-weather response strategy after the incident, it essentially told the elected officials that since building storm shelters isn’t required by law, it won’t do that.
The company responded to lawmakers Senator Elizabeth Warren (D-MA) and Representatives Alexandria Ocasio-Cortez (D-NY) and Cori Bush (D-MO), who sent a letter on December 15th, questioning the company’s lack of storm shelters or safe rooms at its warehouses. “Amazon’s apparent unwillingness to invest in a storm shelter or safe room at its Edwardsville facility is made even more concerning by the fact that installing one could be done by Amazon at relatively low cost,” the lawmakers wrote. “This cost is negligible for a company like Amazon, which brought in more than $500 billion in revenue over the 12-month period ending September 30, 2022 and clearly has the resources necessary to protect its workers should it have the will to do so.”
Company vice president of public policy Brian Huseman responded (via CNBC), “Amazon requires that its buildings follow all applicable laws and building codes. We have not identified any jurisdiction in the United States that requires storm shelters or safe rooms for these types of facilities.”
Lawrence Bryant / reuters
Huseman added that Amazon follows Occupational Safety and Health Administration (OSHA) and National Weather Service guidelines and will continue using a “severe weather assembly area” for sheltering in place instead of the requested storm shelters. The six employees and contractors who died at the warehouse tried to protect themselves in a bathroom; the surviving workers took refuge in an assembly area.
OSHA investigated the incident last April and ordered Amazon to review its severe weather policies, but it fell short of penalizing the company for its response. Additionally, Amazon hired a meteorologist, launched an internal center for monitoring severe weather and created emergency cards pointing out evacuation points and assembly areas.
Amazon reportedly began rebuilding the warehouse last June. The families of two of the employees killed there have sued the company for wrongful death.
Self-driving cars frequently have trouble with poor weather, but Waymo thinks it can overcome these limitations by using its autonomous taxis as weather gauges. The company has revealed that its latest car sensor arrays are creating real-time weather maps to improve ride hailing services in Phoenix and San Francisco. The vehicles measure the raindrops on windows to detect the intensity of conditions like fog or rain.
The technology gives Waymo a much finer-grained view of conditions than it gets from airport weather stations, radar and satellites. It can track the coastal fog as it rolls inland, or drizzle that radar would normally miss. While that's not as important in a dry locale like Phoenix, it can be vital in San Francisco and other cities where the weather can vary wildly between neighborhoods.
There are a number of practical advantages to gathering this data, as you might guess. Waymo is using the info to improve its Driver AI's ability to handle rough weather, including more realistic simulations. The company also believes it can better understand the limits of its cars and set higher requirements for new self-driving systems. The tech also helps Waymo One better serve ride hailing passengers at a given time and place, and gives Waymo Via trucking customers more accurate delivery updates.
The current weather maps have their limitations. They may help in a warm city like San Francisco, where condensation and puddles are usually the greatest problems, but they won't be as useful for navigating snowy climates where merely seeing the lanes can be a challenge. There's also the question of whether or not it's ideal to have cars measure the very conditions that hamper their driving. This isn't necessarily the safest approach.
This could still go a long way toward making Waymo's driverless service more practical, though. Right now, companies like Waymo and Cruise aren't allowed to operate in heavy rain or fog using their California permits — the weather monitoring could help these robotaxi firms serve customers looking for dry rides home.
Self-driving cars frequently have trouble with poor weather, but Waymo thinks it can overcome these limitations by using its autonomous taxis as weather gauges. The company has revealed that its latest car sensor arrays are creating real-time weather maps to improve ride hailing services in Phoenix and San Francisco. The vehicles measure the raindrops on windows to detect the intensity of conditions like fog or rain.
The technology gives Waymo a much finer-grained view of conditions than it gets from airport weather stations, radar and satellites. It can track the coastal fog as it rolls inland, or drizzle that radar would normally miss. While that's not as important in a dry locale like Phoenix, it can be vital in San Francisco and other cities where the weather can vary wildly between neighborhoods.
There are a number of practical advantages to gathering this data, as you might guess. Waymo is using the info to improve its Driver AI's ability to handle rough weather, including more realistic simulations. The company also believes it can better understand the limits of its cars and set higher requirements for new self-driving systems. The tech also helps Waymo One better serve ride hailing passengers at a given time and place, and gives Waymo Via trucking customers more accurate delivery updates.
The current weather maps have their limitations. They may help in a warm city like San Francisco, where condensation and puddles are usually the greatest problems, but they won't be as useful for navigating snowy climates where merely seeing the lanes can be a challenge. There's also the question of whether or not it's ideal to have cars measure the very conditions that hamper their driving. This isn't necessarily the safest approach.
This could still go a long way toward making Waymo's driverless service more practical, though. Right now, companies like Waymo and Cruise aren't allowed to operate in heavy rain or fog using their California permits — the weather monitoring could help these robotaxi firms serve customers looking for dry rides home.
Because nobody likes a wet butt (I only face forward in the shower), the Butt Be Dry (affiliate link) is a portable seating pad to prevent the back of your pants from getting soaked while sitting on a wet seat. Perfect for sports stadiums and the great outdoors, it probably won’t prevent you from getting wet if you decide to sit in a pool, just to be clear.
The 18″ wide pad rolls up to just 3″ when not in use and can be worn around the waist like a fanny pack for hands-free transportation. Available in blue, light blue, green, and camouflage, I can’t recommend buying the camo version unless you want to lose it on a camping trip. I could have sworn I set it on a tree stump around here somewhere!
Alternatively, do what my wife does whenever she doesn’t want to sit on a wet seat and sit on my lap. Why should two people have to suffer when only one can, and that person be you – that’s her motto. Such an angel.
Hurricane season is currently in full swing across the Gulf Coast and Eastern Seaboard. Following a disconcertingly quiet start in June, meteorologists still expect a busier-than-usual stretch before the windy weather (hopefully) winds down at the end of November. Meteorologists like Matthew Cappucci who, in his new book, Looking Up: The True Adventures of a Storm-Chasing Weather Nerd, recounts his career as a storm chaser — from childhood obsession to adulthood obsession as a means of gainful employment. In the excerpt below, Cappucci explains the inner workings of tropical storms.
Hurricanes are heat engines. They derive their fury from warm ocean waters in the tropics, where sea surface temperatures routinely hover in the mid- to upper-eighties between July and October. Hurricanes and tropical storms fall under the umbrella of tropical cyclones. They can be catastrophic, but they have a purpose—some scholars estimate they’re responsible for as much as 10 percent of the Earth’s annual equator-to-pole heat transport.
Hurricanes are different from mid-latitude systems. So-called extratropical, or nontropical, storms depend upon variations in air temperature and density to form, and feed off of changing winds. Hurricanes require a calm environment with gentle upper-level winds and a nearly uniform temperature field. Ironic as it may sound, the planet’s worst windstorms are born out of an abundance of tranquility.
The first ingredient is a tropical wave, or clump of thunderstorms. Early in hurricane season, tropical waves can spin up on the tail end of cold fronts surging off the East Coast. During the heart of hurricane season in August and September, they commonly materialize off the coast of Africa in the Atlantic’s Main Development Region. By October and November, sneaky homegrown threats can surreptitiously gel in the Gulf of Mexico or Caribbean.
Every individual thunderstorm cell within a tropical wave has an updraft and a downdraft. The downward rush of cool air collapsing out of one cell can suffocate a neighboring cell, spelling its demise. In order for thunderstorms to coexist in close proximity, they must organize. The most efficient way of doing so is through orienting themselves around a common center, with individual cells’ updrafts and downdrafts working in tandem.
When a center forms, a broken band of thunderstorms begins to materialize around it. Warm, moist air rises within those storms, most rapidly as one approaches the broader system’s low-level center. That causes atmospheric pressure to drop, since air is being evacuated and mass removed. From there, the system begins to breathe.
Air moves from high pressure to low pressure. That vacuums air inward toward the center. Because of the Coriolis force, a product of the Earth’s spin, parcels of air take a curved path into the fledgling cyclone’s center. That’s what causes the system to rotate.
Hurricanes spin counterclockwise in the Northern Hemisphere, and clockwise south of the equator. Though the hottest ocean waters in the world are found on the equator, a hurricane could never form there. That’s because the Coriolis force is zero on the equator; there’d be nothing to get a storm to twist.
As pockets of air from outside the nascent tropical cyclone spiral into the vortex, they expand as barometric pressure decreases. That releases heat into the atmosphere, causing clouds and rain. Ordinarily that would result in a drop in temperature of an air parcel, but because it’s in contact with toasty ocean waters, it maintains a constant temperature; it’s heated at the same rate that it’s losing temperature to its surroundings. As long as a storm is over the open water and sea surface temperatures are sufficiently mild, it can continue to extract oceanic heat content.
Rainfall rates within tropical cyclones can exceed four inches per hour thanks to high precipitation efficiency. Because the entire atmospheric column is saturated, there’s little evaporation to eat away at a raindrop on the way down. As a result, inland freshwater flooding is the number one source of fatalities from tropical cyclones.
The strongest winds are found toward the middle of a tropical storm or hurricane in the eyewall. The greatest pressure gradient, or change of air pressure with distance, is located there. The sharper the gradient, the stronger the winds. That’s because air is rushing down the gradient. Think about skiing — you’ll ski faster if there’s a steeper slope.
When maximum sustained winds surpass 39 mph, the system is designated a tropical storm. Only once winds cross 74 mph is it designated a hurricane. Major hurricanes have winds of 111 mph or greater and correspond to Category 3 strength. A Category 5 contains extreme winds topping 157 mph.
Since the winds are derived from air rushing in to fill a void, or deficit of air, the fiercest hurricanes are usually those with the lowest air pressures. The most punishing hurricanes and typhoons may have a minimum central barometric pressure about 90 percent of ambient air pressure outside the storm. That means 10 percent of the atmosphere’s mass is missing.
Picture stirring your cup of coffee with a teaspoon. You know that dip in the middle of the whirlpool? The deeper the dip, or fluid deficit, the faster the fluid must be spinning. Hurricanes are the same. But what prevents that dip from filling in? Hurricane eyewalls are in cyclostrophic balance.
That means a perfect stasis of forces makes it virtually impossible to “fill in” a storm in steady state. Because of their narrow radius of curvature, parcels of air swirling around the eye experience an incredible outward-directed centrifugal force that exactly equals the inward tug of the pressure gradient force. That leaves them to trace continuous circles.
If you’ve ever experienced a change in altitude, such as flying on an airplane, or even traveling to the top of a skyscraper, you probably noticed your ears popping. That’s because they were adjusting to the drop in air pressure with height. Now imagine all the air below that height vanished. That’s the equivalent air pressure in the eye a major hurricane. The disparity in air pressure is why a hurricane is, in the words of Buddy the Elf, “sucky. Very sucky.”
Sometimes hurricanes undergo eyewall replacement cycles, which entail an eyewall shriveling and crumbling into the eye while a new eyewall forms around it and contracts, taking the place of its predecessor. This usually results in a dual wind maximum near the storm’s center as well as a brief plateau in intensification.
In addition to the scouring winds found inside the eyewall, tornadoes, tornado-scale vortices, mini swirls, and other poorly understood small-scale wind phenomena can whip around the eye and result in strips of extreme damage. A mini swirl may be only a couple yards wide, but a 70 mph whirlwind moving in a background wind of 100 mph can result in a narrow path of 170 mph demolition. Their existence was first hypothesized following the passage of Category 5 Hurricane Andrew through south Florida in 1992, and modern-day efforts to study hurricane eyewalls using mobile Doppler radar units have shed light on their existence. Within a hurricane’s eye, air sinks and warms, drying out and creating a dearth of cloud cover. It’s not uncommon to see clearing skies or even sunshine. The air is hot and still, an oasis of peace enveloped in a hoop of hell.
There’s such a discontinuity between the raucous winds of the eyewall and deathly stillness of the eye that the atmosphere struggles to transition. The eyes of hurricanes are often filled with mesovortices, or smaller eddies a few miles across, that help flux and dissipate angular momentum into the eye. Sometimes four or five mesovortices can cram into the eye, contorting the eyewall into a clover-like shape. That makes for a period of extraordinary whiplash on the inner edge of the eyewall as alternating clefts of calamitous wind and calm punctuate the eye’s arrival.
Hurricane season is currently in full swing across the Gulf Coast and Eastern Seaboard. Following a disconcertingly quiet start in June, meteorologists still expect a busier-than-usual stretch before the windy weather (hopefully) winds down at the end of November. Meteorologists like Matthew Cappucci who, in his new book, Looking Up: The True Adventures of a Storm-Chasing Weather Nerd, recounts his career as a storm chaser — from childhood obsession to adulthood obsession as a means of gainful employment. In the excerpt below, Cappucci explains the inner workings of tropical storms.
Hurricanes are heat engines. They derive their fury from warm ocean waters in the tropics, where sea surface temperatures routinely hover in the mid- to upper-eighties between July and October. Hurricanes and tropical storms fall under the umbrella of tropical cyclones. They can be catastrophic, but they have a purpose—some scholars estimate they’re responsible for as much as 10 percent of the Earth’s annual equator-to-pole heat transport.
Hurricanes are different from mid-latitude systems. So-called extratropical, or nontropical, storms depend upon variations in air temperature and density to form, and feed off of changing winds. Hurricanes require a calm environment with gentle upper-level winds and a nearly uniform temperature field. Ironic as it may sound, the planet’s worst windstorms are born out of an abundance of tranquility.
The first ingredient is a tropical wave, or clump of thunderstorms. Early in hurricane season, tropical waves can spin up on the tail end of cold fronts surging off the East Coast. During the heart of hurricane season in August and September, they commonly materialize off the coast of Africa in the Atlantic’s Main Development Region. By October and November, sneaky homegrown threats can surreptitiously gel in the Gulf of Mexico or Caribbean.
Every individual thunderstorm cell within a tropical wave has an updraft and a downdraft. The downward rush of cool air collapsing out of one cell can suffocate a neighboring cell, spelling its demise. In order for thunderstorms to coexist in close proximity, they must organize. The most efficient way of doing so is through orienting themselves around a common center, with individual cells’ updrafts and downdrafts working in tandem.
When a center forms, a broken band of thunderstorms begins to materialize around it. Warm, moist air rises within those storms, most rapidly as one approaches the broader system’s low-level center. That causes atmospheric pressure to drop, since air is being evacuated and mass removed. From there, the system begins to breathe.
Air moves from high pressure to low pressure. That vacuums air inward toward the center. Because of the Coriolis force, a product of the Earth’s spin, parcels of air take a curved path into the fledgling cyclone’s center. That’s what causes the system to rotate.
Hurricanes spin counterclockwise in the Northern Hemisphere, and clockwise south of the equator. Though the hottest ocean waters in the world are found on the equator, a hurricane could never form there. That’s because the Coriolis force is zero on the equator; there’d be nothing to get a storm to twist.
As pockets of air from outside the nascent tropical cyclone spiral into the vortex, they expand as barometric pressure decreases. That releases heat into the atmosphere, causing clouds and rain. Ordinarily that would result in a drop in temperature of an air parcel, but because it’s in contact with toasty ocean waters, it maintains a constant temperature; it’s heated at the same rate that it’s losing temperature to its surroundings. As long as a storm is over the open water and sea surface temperatures are sufficiently mild, it can continue to extract oceanic heat content.
Rainfall rates within tropical cyclones can exceed four inches per hour thanks to high precipitation efficiency. Because the entire atmospheric column is saturated, there’s little evaporation to eat away at a raindrop on the way down. As a result, inland freshwater flooding is the number one source of fatalities from tropical cyclones.
The strongest winds are found toward the middle of a tropical storm or hurricane in the eyewall. The greatest pressure gradient, or change of air pressure with distance, is located there. The sharper the gradient, the stronger the winds. That’s because air is rushing down the gradient. Think about skiing — you’ll ski faster if there’s a steeper slope.
When maximum sustained winds surpass 39 mph, the system is designated a tropical storm. Only once winds cross 74 mph is it designated a hurricane. Major hurricanes have winds of 111 mph or greater and correspond to Category 3 strength. A Category 5 contains extreme winds topping 157 mph.
Since the winds are derived from air rushing in to fill a void, or deficit of air, the fiercest hurricanes are usually those with the lowest air pressures. The most punishing hurricanes and typhoons may have a minimum central barometric pressure about 90 percent of ambient air pressure outside the storm. That means 10 percent of the atmosphere’s mass is missing.
Picture stirring your cup of coffee with a teaspoon. You know that dip in the middle of the whirlpool? The deeper the dip, or fluid deficit, the faster the fluid must be spinning. Hurricanes are the same. But what prevents that dip from filling in? Hurricane eyewalls are in cyclostrophic balance.
That means a perfect stasis of forces makes it virtually impossible to “fill in” a storm in steady state. Because of their narrow radius of curvature, parcels of air swirling around the eye experience an incredible outward-directed centrifugal force that exactly equals the inward tug of the pressure gradient force. That leaves them to trace continuous circles.
If you’ve ever experienced a change in altitude, such as flying on an airplane, or even traveling to the top of a skyscraper, you probably noticed your ears popping. That’s because they were adjusting to the drop in air pressure with height. Now imagine all the air below that height vanished. That’s the equivalent air pressure in the eye a major hurricane. The disparity in air pressure is why a hurricane is, in the words of Buddy the Elf, “sucky. Very sucky.”
Sometimes hurricanes undergo eyewall replacement cycles, which entail an eyewall shriveling and crumbling into the eye while a new eyewall forms around it and contracts, taking the place of its predecessor. This usually results in a dual wind maximum near the storm’s center as well as a brief plateau in intensification.
In addition to the scouring winds found inside the eyewall, tornadoes, tornado-scale vortices, mini swirls, and other poorly understood small-scale wind phenomena can whip around the eye and result in strips of extreme damage. A mini swirl may be only a couple yards wide, but a 70 mph whirlwind moving in a background wind of 100 mph can result in a narrow path of 170 mph demolition. Their existence was first hypothesized following the passage of Category 5 Hurricane Andrew through south Florida in 1992, and modern-day efforts to study hurricane eyewalls using mobile Doppler radar units have shed light on their existence. Within a hurricane’s eye, air sinks and warms, drying out and creating a dearth of cloud cover. It’s not uncommon to see clearing skies or even sunshine. The air is hot and still, an oasis of peace enveloped in a hoop of hell.
There’s such a discontinuity between the raucous winds of the eyewall and deathly stillness of the eye that the atmosphere struggles to transition. The eyes of hurricanes are often filled with mesovortices, or smaller eddies a few miles across, that help flux and dissipate angular momentum into the eye. Sometimes four or five mesovortices can cram into the eye, contorting the eyewall into a clover-like shape. That makes for a period of extraordinary whiplash on the inner edge of the eyewall as alternating clefts of calamitous wind and calm punctuate the eye’s arrival.
