How Are Hurricane Categories Determined?

Satellite photo of Hurricane Dorian, a Category 5 storm, tracks toward the Florida coast on September 1, 2019.
Satellite photo of Hurricane Dorian, a Category 5 storm, tracks toward the Florida coast on September 1, 2019.
NOAA via Getty Images

Residents of the Bahamas are in the midst of Hurricane Dorian, a Category 5 storm that prime minister Hubert Minnis said has already caused "unprecedented" devastation to the area. Meanwhile, residents of Florida, Georgia, and the Carolinas are being evacuated ahead of the storm's potential arrival in the U.S. At this point, we've become accustomed to hearing about hurricanes, and to predicting what sort of damage they might cause based on their category number. But how do meteorologists categorize these often-deadly storms, and how does that scale work?

First, a quick primer: Hurricanes are tropical cyclones that occur in the Atlantic Ocean and have winds with a sustained speed of at least 74 mph. A tropical cyclone, in turn, is a storm system that develops in the tropics and is characterized by a low pressure center and thunderstorms that produce strong winds, rain, and storm surges. Tropical cyclone is a generic name that refers to the storms' geographic origin and cyclonic rotation around a central eye. Depending on their location and strength, the storms are called different things. What gets dubbed a hurricane in the Atlantic, for example, would be called a typhoon if it happened in the northwestern Pacific.

What's the difference between a hurricane and a tropical storm?

Simply put: Wind speed. When tropical cyclones are just starting out as general areas of low pressure with the potential to strengthen, they’re called tropical depressions. They’re given sequential numbers as they form during a storm season so the National Hurricane Center (NHC) can keep tabs on them.

Once a cyclone’s winds kick up to 39 miles per hour and sustain that speed for 10 minutes, it becomes a tropical storm and the NHC gives it a name. If the cyclone keeps growing and sustains 74 mph winds, it graduates to hurricane.

Once we call it a hurricane, how do we categorize it?

In order to assign a numeric category value to a hurricane, meteorologists look to the Saffir-Simpson Hurricane Wind Scale, which was developed as a classification system for Western Hemisphere tropical cyclones in the late 1960s and early '70s by structural engineer Herbert Saffir and his friend, meteorologist Robert Simpson, who was the director of the NHC at the time.

When Saffir was working on a United Nations project to study low-cost housing in hurricane-prone areas, it struck him that there was no simple, standardized way of describing hurricanes and their damaging effects, like the way the Richter scale is used to describe earthquakes. He created a five-level scale based on wind speed and sent it off to Simpson, who expanded on it to include the effects on storm surge and flooding. Simpson began using it internally at the NHC, and then in reports shared with emergency agencies. It proved useful, so others began adopting it and it quickly spread.

How does the scale work?

According to the NHC, the scale breaks down like this:

Category 1 storms have sustained winds of 74 to 95 mph. These “very dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding, and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days."

Category 2 storms have sustained winds of 96 to 110 mph. These “extremely dangerous winds will cause extensive damage: Well-constructed frame homes could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks."

Category 3 storms have sustained winds of 111 to 129 mph. This is the first category that qualifies as a “major storm” and “devastating damage will occur: Well-built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes."

Category 4 storms have sustained winds of 130 to 156 mph. These storms are “catastrophicand damage includes: “Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months."

Category 5 storms have sustained winds of 157 mph or higher. The catastrophic damage entailed here includes: “A high percentage of framed homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months."

While the Saffir-Simpson scale is useful, it isn’t the be-all and end-all for measuring storms, as the National Oceanic and Atmospheric Administration (NOAA) pointed out on Twitter in 2013:

Is there anything worse than a category 5?

Not on paper, but there have been hurricanes that have gone beyond the upper bounds of the scale. Hypothetically, hurricanes could up the ante beyond Category 5 more regularly. The storms use warm water to fuel themselves and as ocean temperatures rise, climatologists predict that potential hurricane intensity will increase.

Both Saffir and Simpson have said that there’s no need to add more categories because once things go beyond 157 mph, the damage all looks the same: really, really bad. Still, that hasn't stopped several scientists from suggesting that maybe the time has come to consider a Category 6 addition.

Timothy Hall, a senior scientist at NASA's Goddard Institute for Space Studies, recently told the Los Angeles Times that if the current global warming trends continue, he can foresee a time—likely by the end of the century—where wind speeds could blow past 230 mph, which could create conditions similar to a F-4 tornado (which has the power to lift cars off the ground and send them hurtling through the air with relative ease).

“If we had twice as many Category 5s—at some point, several decades down the line—if that seems to be the new norm, then yes, we’d want to have more partitioning at the upper part of the scale,” Hall said. “At that point, a Category 6 would be a reasonable thing to do."

An earlier version of this article appeared in 2013.

Why Do So Many News Anchors Sound Alike?

News anchors have mastered the art of being linguistically neutral.
News anchors have mastered the art of being linguistically neutral.
iofoto/iStock via Getty Images

No matter which channel you tune into or what local broadcast you receive, news anchors share one common trait beyond professional attire and perfect hair. They tend to sound exactly the same, from their cadence to enunciation to a completely curious lack of a regional accent. How does that happen?

Broadcasters didn’t always sound so geographically neutral. In the early part of the 20th century, many radio personalities and performers adopted what was known as a Mid-Atlantic accent, or a blend of mannered British and the East Coast dialect of the United States. This polished, proper method of speaking was popular in Hollywood movies of the 1930s and on radio because it signaled some kind of upper-class education and erudition. Thanks to America’s infatuation with England, sounding even vaguely British made people sound intelligent. Pundits like William F. Buckley Jr. carried the Mid-Atlantic torch even as it fell out of favor in entertainment.

The more contemporary practice of sounding linguistically neutral is often referred to as having a General American accent—which is a bit misleading, since there’s really not much of an accent at all. Also referred to as Standard American, Broadcast English, or Network English, General American was a term first used in the 1920s and '30s by linguists who wanted to isolate a more widespread accent than the New England or Southern dialects. The scholar George Philip Krapp used the phrase in his 1925 book The English Language in America; linguist John Kenyon referred to it in his 1930 title American Pronunciation, where he insisted that 90 million Americans spoke General American.

As the century wore on, a wider range of regional accents were recognized, and it became almost impossible to generalize between New England, Southern, and General American. Though some linguists disagree on the definition of General American, it’s still largely considered a speaking voice that lacks regional flair.

So why do news anchors rely on it? One of the biggest reasons is to keep their employment opportunities open. Local anchors who deliver the nightly news for affiliate stations are often vagabonds, taking jobs across the country, and those different networks prefer a General American accent. If an anchor hailing from the South committed to delivering the day’s top stories in a Southern accent, for example, it’s not likely a New York station would feel viewers could warm to them. Likewise, a Brooklyn accent might sound peculiar when Los Angeles residents want a rundown of local headlines.

But an accent is only a portion of a broadcaster’s delivery. At broadcasting schools, television journalists are trained to speak at a moderate speed and enunciate each word clearly. (Whether they realize it or not, young broadcasters may also start out emulating their news anchor heroes who had impeccable diction, like Walter Cronkite or Ted Koppel.) No letters are dropped. Sentences are composed for ease of reading off a teleprompter.

Plain speaking also needs to fit whatever footage is being shown while the anchor is talking. Uneven modulation could be distracting, though some anchors do choose to emphasize words by drawing them out (“muur-der”) or adopt a more somber tone when reporting on tragic events.

Some anchors have also reported being more careful with their speech because broadcast microphones are often unforgiving. Words beginning with P tend to pop, for example. Broadcasting school drills out the kind of casual and conversational voice that doesn’t translate well to a newscast.

Of course, some linguists believe there’s no such thing as being totally free of an accent. A Southerner trying to remove any trace of a drawl is going to sound different than someone from New England attempting to do the same. We may not notice simply because humans aren’t that great at recognizing more subtle accents, especially our own. Broadcasters may sound alike in large part because they all enunciate and attempt to achieve articulatory precision. Few anchors will say “dubya.” They will say “double-you.” But that occasional “dubya” is what makes speech patterns sound different.

And that’s all the news we have today.

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Why Does the Queen Have Two Birthdays?

Toby Melville, WPA Pool/Getty Images
Toby Melville, WPA Pool/Getty Images

On April 21, 2020 Her Majesty Queen Elizabeth II will turn 94 years old. To mark the occasion, there are usually a series of gun salutes around London: a 41 gun salute in Hyde Park, a 21 gun salute in Windsor Great Park, and a 62 gun salute at the Tower of London. For the most part, the monarch celebrates her big day privately. But in June, Her Majesty typically parades through London as part of an opulent birthday celebration known as Trooping the Colour (though this year's fête has been cancelled due to the coronavirus pandemic).

Queen Elizabeth, like many British monarchs before her, has two birthdays: the actual anniversary of the day she was born, and a separate day that is labeled her "official" birthday (usually the second Saturday in June). Why? Because April 21 is usually too cold for a proper parade.

The tradition started in 1748, with King George II, who had the misfortune of being born in chilly November. Rather than have his subjects risk catching colds, he combined his birthday celebration with the Trooping the Colour.

The parade itself had been part of British culture for almost a century by that time. At first it was strictly a military event, at which regiments displayed their flags—or colours—so that soldiers could familiarize themselves. But George was known as a formidable general after having led troops at the Battle of Dettingen in 1743, so the military celebration seemed a fitting occasion onto which to graft his warm-weather birthday. Edward VII, who also had a November birthday, was the first to standardize the June Trooping the Colour and launched a tradition of a monarchical review of the troops that drew crowds of onlookers.

Even now, the date of the "official" birthday varies year to year. For the first seven years of her reign, Elizabeth II held her official birthday on a Thursday but has since switched over to Saturdays. And while the date is tied to the Trooping the Colour in the UK, Commonwealth nations around the world have their own criteria, which generally involve recognizing it as a public holiday.

Australia started recognizing an official birthday back in 1788, and all the provinces (save one) observe the Queen's Birthday on the second Monday in June, with Western Australia holding its celebrations on the last Monday of September or the first Monday of October.

In Canada, the official birthday has been set to align with the actual birth date of Queen Victoria—May 24, 1819—since 1845, and as such they celebrate so-called Victoria Day on May 24 or the Monday before.

In New Zealand, it's the first Monday in June, and in the Falkland Islands the actual day of the Queen's birth is celebrated publicly.

All in all, just another reason it's great to be Queen.

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