We seem to be hearing a lot about hurricanes, lately. Are we seeing more of them? Or are they just more destructive? Or is it a combination of both? Is hurricane season getting longer? There’s no doubt that, as the climate changes, climate phenomena like storms are changing as well. But what can we expect in the future? Read on to learn more about hurricanes, and how our changing climate is changing them as well.

A Few Definitions

Hurricane? Cyclone? Typhoon? What’s the difference? Location, location, location. The words all describe a tropical storm, but people in different places use different names. Storms in the Atlantic Ocean, the Caribbean, and the central and northeast Pacific are called hurricanes. When these storms occur in the northwest Pacific, they call them typhoons. They’re cyclones in the Bay of Bengal and the Arabian Sea. And in the southwest Indian Ocean, they’re tropical cyclones.

The Eye of a hurricane is the hole that you see in the center of the storm. The weather may be clear in this area, the skies partly sunny, and the winds may be light.

The Eye Wall is a ring of thunderstorms that swirl around the eye. This part of the hurricane has the strongest winds and the heaviest rainfall.

Rain Bands are spiral bands of clouds, rain, and thunderstorms that extend out from the eyewall. These bands can stretch for hundreds of miles and sometimes contain tornadoes.

The Storm Surge is a wall of water that rushes inland, like a tsunami. Storm surges result from a complex combination of storm-related phenomena, which include water pressure, wind, rainfall, and more.

How Do Hurricanes Form?

Hurricanes have two main ingredients: warm water and winds that rise while maintaining the same direction and speed. Predictions about an increase in hurricane frequency and/or intensity are partly based on the fact that sea temperatures are rising. Warmer water — and more warm water — may mean a longer hurricane season, more hurricanes, and stronger ones.

A hurricane forms from an ocean storm. This process has several steps.

First, a tropical disturbance forms. A tropical disturbance is an area over warm ocean waters, where rain clouds gather. Next, a tropical disturbance grows into a tropical depression. A tropical depression is an area of rotating thunderstorms with winds of less than 38 miles per hour. When those wind speeds reach 39 miles per hour, the depression becomes a tropical storm. Finally, a tropical storm becomes a hurricane, when its wind speeds reach 74 miles per hour.

Warm ocean waters provide the energy needed for a storm to become a hurricane. Usually, the surface water temperature must be 79 degrees Fahrenheit or higher for a hurricane to form. Because one element of climate change is rising ocean temperatures, many climate models are predicting more frequent hurricanes.

What’s in a name?

Hurricanes have names, and meteorologists classify them in terms of categories. How are they named? What do the categories mean? Take a look.

Hurricane strength

National Hurricane Center levels of hurricanes and their strengths.

Image: Public Domain, by NOAA’s National Weather Service, via NOAA Photo Library

Category 1

Category one hurricanes have winds from 74 to 95 miles per hour. That’s faster than a cheetah can run!

Category 2

Category two storms have wind speeds of 96 to 110 miles per hour. That’s a bit faster than a baseball pitcher’s fastest fastball speed.

Category 3

A category three storm has wind speeds of 111 to 129 miles per hour. That’s close to the serving speed of many professional tennis players.

Category 4

A category four storm has wind speeds of 130 to 156 miles per hour, and that’s faster than the world’s fastest roller coaster.

Category 5

A category five storm, like Hurricane Katrina, has winds above 157 miles per hour. This is about as fast as a high-speed train.

How do meteorologists name hurricanes?

The World Meteorological Organization maintains a list of names. The names are ones that are familiar in each region. If a hurricane causes a lot of damage or deaths one year (for example Katrina in 2005), the organization takes the name off the list to avoid future confusion.

Meteorologists have been naming hurricanes for about 100 years. They used to use arbitrary names. Then, in the mid-1900s, they started using female names. Eventually, they started to use an alphabetical rotation of names. In 1953, the National Hurricane Center started keeping lists for storms originating in the Caribbean Sea, Gulf of Mexico, and the North Atlantic. The lists used to only contain female names, but the National Hurricane Center began adding male names in 1979. Today, the list is maintained by the World Meteorological Organization.

Some Famous Hurricanes

Hurricane Katrina in 2005 was one of the most devastating natural disasters in American history. It was also the first time that the connection between weather events and climate change entered the public conversation in such a big way. Since Katrina, extreme weather events seem to be on the rise. In addition, they seem to be more violent, more destructive, and costlier than ever before. In addition, the 2017 Atlantic hurricane season saw an unusual number of severe weather events. Are these events due to climate change? Many people believe that they are.

August / September 2005: Hurricane Katrina

Katrina, a Category 5 hurricane, was the costliest natural disaster on record, causing $160 billion in damage and destroying huge amounts of land and property along the Gulf of Mexico. Some of the most dramatic and memorable damage was to the city of New Orleans, Louisiana. Nearly 80 percent of New Orleans was flooded due to the failure of the levees holding back Lake Ponchartrain. In addition, large tracts of land in Florida, Louisiana, Mississippi, and other parts of the southeastern United States were badly damaged. Places as far away as Cuba and the Bahamas also saw damage. Katrina caused 1,833 deaths, and the city of New Orleans is still recovering, all these years later.

August / September 2017: Hurricane Irma

Hurricane Irma was the strongest Atlantic hurricane ever recorded outside the Gulf of Mexico and the Caribbean. Irma, also a Category 5 hurricane, stretched 650 miles from east to west. It caused damage in at least nine southeastern U.S. states, including Florida and South Carolina. The video above from NASA details Irma’s path over its 10-day lifespan.

August 2017: Hurricane Harvey

Hurricane Harvey image from NASA.

Image: Public Domain, by NASA, via Wikimedia Commons.

Harvey, a Category 4 hurricane, was the second costliest hurricane on record after Katrina. It caused $125 billion in damage, mostly in Texas and Arkansas. Harvey made landfall three times over the course of six days. Flooding forced 39,000 people out of their homes. In addition, Harvey destroyed 800 wastewater treatment facilities and 13 toxic waste disposal sites, flooding the land with sewage and toxic waste. Miraculously, only 106 people died. Arkansas County saw a storm surge of 12.5 feet. And the storm forced 25 percent of oil and gas production to shut down — that’s 5 percent of national oil and gas production.

September 2017: Hurricane Maria

Hurricane Maria, another Category 5 hurricane, was the deadliest storm of the 2017 Atlantic Hurricane season. And that’s saying something. Experts called the 2017 season “hyperactive.” There were 17 named storms, and all 10 of the season’s hurricanes occurred one right after the other. 112 people died, and the island of Dominica received catastrophic damage. In Puerto Rico, many still remain without food or power, as detailed in the video above.

Hurricanes and Climate Change

Hurricane Katrina in 2005 forced many people to rethink their views on hurricane and climate change. People began to wonder if climate change would cause hurricane season to become longer. Studies done since then have had conflicting results. However, a few trends have emerged, including the fact that there are definitely more hurricanes at the beginning and end of hurricane season. In addition, there are more major hurricanes.

Yes, we are seeing more hurricanes

In the last 26 years, late-season hurricanes have become three times more frequent. The 2017 Atlantic hurricane season saw 17 named storms, and 10 hurricanes, one right after another. In addition, 2017 was one of only six years on record to feature more than one Category 5 hurricane. There were two, and they both made landfall at that speed. Experts called the 2017 Atlantic hurricane season “hyperactive,” and many are wondering what the 2018 season will bring.

Yes, hurricanes are getting stronger

Major hurricanes have also become more frequent in the past 26 years. Many scientists agree that the 2017 hurricane season, specifically Harvey, Irma, and Rita, was more destructive because of warmer water temperatures. According to Kerry Emanuel, an atmospheric sciences professor at the Massachusetts Institute of Technology, warmer sea temperatures led to higher wind speeds during Hurricane Harvey, which led to greater destruction on land. In addition, Emmanuel’s research predicts that storms with Harvey’s destructive capacity may become more frequent — once every five to 10 years, instead of once in a century.

Michael Wehner, a senior staff scientist at the Department of Energy’s Lawrence Berkeley National Laboratory, considers it “more likely than not” that climate change contributed to Harvey’s last-minute burst of strength.

What Can We do?

There’s not a lot we can do to stop hurricanes from forming. But we can be prepared.

First, if you live in a hurricane-prone area, have an evacuation plan and be prepared to use it. Know where the nearest shelters are and how to get there.

Second, have a go-bag. This should include a flashlight, batteries, cash, first aid supplies, medications, and copies of your critical information if you need to evacuate.

Third, have a family emergency plan. Ready.gov has some excellent information that can help you formulate it.

In addition, if you’re concerned about climate change, learn more about your carbon footprint. And learn what measures you, personally, can take, in order to reduce it.


Featured Image: CC0 Creative Commons, by 12019, via Pixabay.

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