Where Do Hurricanes Come From?

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Robyn Auld
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5.8

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Hurricanes are a kind of tropical cyclone. But where do they come from? And why do they cause so much damage? This article will answer all your storm-related questions!

Where might you see a deadly hurricane in Canada? The east coast? That’s a good answer. One storm in 1775 killed more than 4000 people in Newfoundland! But hurricanes can also affect regions much further inland. Hurricane Hazel, one of the deadliest storms in Canadian history, hit Toronto in 1954. 

Storm track of Hurricane Hazel, which reached into southern Ontario
Storm track of Hurricane Hazel, which reached into southern Ontario (Source: Supportstorm [Public domain] via Wikimedia Commons).

Hurricane Hazel killed hundreds of people in Haiti. It continued along the Atlantic coast of the United States. There, it killed dozens more people. It also caused almost $300 million in damage. 

The remnants of Hurricane Hazel made it to southern Ontario. Heavy rains flooded streets and washed out bridges in Toronto. A total of 81 Canadians died in the storm. 

Hurricanes are a kind of tropical cyclone. Tropical cyclones are intense storms that form in tropical oceans. They usually start near the equator. These storms have strong, circular winds and heavy rain. 

Tropical cyclones are called different things. It all depends on where they start. Hurricanes start near the Caribbean, Mexico and Central America. Typhoons start near the Philippines, China and Japan. In the South Pacific and the Indian Ocean, these storms are just called cyclones

This map shows the tracks of all tropical cyclones which formed worldwide from 1985 to 2005
This map shows the tracks of all tropical cyclones which formed worldwide from 1985 to 2005 (Source: Let’s Talk Science using an image by Nilfanion [Public domain] via Wikimedia Commons).

 

How does a hurricane form?

All tropical cyclones, including hurricanes, develop in the same way. The ocean needs to be at least 26.5 degrees Celsius for a hurricane to form. When wind blows across the warm ocean water, the warm, moist air rapidly rises. As it rises, the moist air cools and the water in it condenses into large storm clouds. The cooling water also releases a lot of heat. This heat transfer creates enough energy to cause strong winds.

These winds push even more warm air up from the ocean surface. More clouds and more wind make the storm more intense. Rapidly moving air creates an area of low pressure at the centre of the hurricane. This is called the “eye of the storm.” It’s usually very calm. However, the area around the eye has the most violent winds.

Engines of Destruction (2016) by It's Okay To Be Smart (6:34 min.).

The Coriolis effect causes a hurricane to move in a circle. The rotation of the Earth makes tropical cyclones rotate clockwise in the Southern hemisphere. And it makes them rotate counterclockwise in the Northern hemisphere. Hurricanes develop north of the equator. So they all rotate counterclockwise!

Each stage of a hurricane has a different name:

  • A tropical disturbance is a cluster of clouds and thunderstorms that may become a hurricane. 

  • A tropical depression has wind speeds between 40 and 62 km/h. 

  • Tropical storms have wind speeds over 62.5 km/h. 

  • And when winds reach 119 km/h, a hurricane officially becomes a tropical cyclone

There are five classes of hurricanes. They’re based on the Saffir-Simpson Scale. A Class 1 hurricane may cause “some damage.” A Class 5 hurricane can cause “extreme damage.” 

The five categories of the Saffir-Simpson Hurricane Wind Scale
The five categories of the Saffir-Simpson Hurricane Wind Scale (©2019 Let’s Talk Science)
Infographic - Text Version

Category one storms can have winds ranging from 119 to 153 kilometres per hour. Category two storms can have winds ranging from 154 to 177 kilometres per hour. Category three storms can have winds ranging from 178 to 208 kilometres per hour. Category four storms can have winds ranging from 209 to 251 kilometres per hour. Category five storms can have winds greater than 252 kilometres per hour. Storm damage can range from some, to extensive to extreme.


When a tropical depression becomes a tropical storm, it gets a name. Atlantic hurricanes are named according to a list. It alternates between male and female names and gets updated every six years. If a storm causes significant damage, its name will be retired. For example, there will never be another hurricane named Hazel.

Did you know?

The most powerful Atlantic storm ever was Hurricane Wilma. It tore through the Caribbean and the southern United States in 2005. It had peak wind speeds of over 296 km/h!

Damage from Hurricane Hazel along the Humber River in Toronto
Damage from Hurricane Hazel along the Humber River in Toronto (Source: James Victor Salmon [Public domain] via Wikimedia Commons).

What are some of the effects of hurricanes?

Hurricanes get their strength from warm tropical waters. They tend to die out pretty quickly when they hit land or colder waters. This is why even coastal parts of Canada don’t experience the full force of these storms. However, even weakened hurricanes can cause a lot of damage. Just ask someone who lived in Toronto, Ontario in 1954!

Along with high winds, hurricanes can bring extreme rainfall. Many storms drop hundreds of millimetres of rain on an area before moving on. Many people get trapped, or even drown. Flooding from a hurricane can also cause millions or even billions of dollars worth of damage. Storms also leave behind contaminated water that can spread disease. 

Did you know?

In 2012, Hurricane Sandy hit the northeastern United States. The storm caused widespread power outages. It also disrupted the local fuel supply chain, causing a major gasoline shortage

Hurricanes also affect natural environments. For example, storm surges or high waves can damage coral reefs.

But these massive storms also have some benefits. They can help to flush out wetlands and lagoons in tropical areas. This removes waste and brings in fresh water and nutrients. Hurricanes also move large masses of very warm air northward. This helps lower temperatures in tropical regions.

Hurricanes are fascinating weather systems. The more scientists learn about them, the better we can prepare for storms like Hurricane Hazel!

Starting Points

Connecting and Relating

  • What hurricanes have you heard about before? Have you ever experienced a hurricane firsthand? What was it like? 

  • Do you know how hurricanes are named? What would you name a hurricane? 

  • What comes to your mind when you hear reports of an approaching hurricane? 

Connecting and Relating

  • What hurricanes have you heard about before? Have you ever experienced a hurricane firsthand? What was it like? 

  • Do you know how hurricanes are named? What would you name a hurricane? 

  • What comes to your mind when you hear reports of an approaching hurricane? 

Relating Science and Technology to Society and the Environment

  • What impacts can a hurricane or cyclone have on the natural environment? 

  • We are often very aware of the short-term impacts of a hurricane, but what can be some of the long-term impacts of a major hurricane event? Consider the various social, economic and ethical issues that may result. 

Relating Science and Technology to Society and the Environment

  • What impacts can a hurricane or cyclone have on the natural environment? 

  • We are often very aware of the short-term impacts of a hurricane, but what can be some of the long-term impacts of a major hurricane event? Consider the various social, economic and ethical issues that may result. 

Exploring Concepts

  • What is the difference between a tropical cyclone and a hurricane? 

  • What conditions must exist to initiate a hurricane? What role does heat transfer play in establishing a hurricane? 

  • Outline the stages in the development of a tropical cyclone. 

  • How is the size of hurricane measured? 

  • Conduct research to find out more about the incidence of hurricanes and cyclones to hit Canada over the years. During what months of the year are hurricanes and cyclones most common? 

  • Describe the naming convention for hurricanes. Why are hurricanes names sometimes retired?

Exploring Concepts

  • What is the difference between a tropical cyclone and a hurricane? 

  • What conditions must exist to initiate a hurricane? What role does heat transfer play in establishing a hurricane? 

  • Outline the stages in the development of a tropical cyclone. 

  • How is the size of hurricane measured? 

  • Conduct research to find out more about the incidence of hurricanes and cyclones to hit Canada over the years. During what months of the year are hurricanes and cyclones most common? 

  • Describe the naming convention for hurricanes. Why are hurricanes names sometimes retired?

Nature of Science/Nature of Technology

  • What aspects of hurricanes are scientists actively researching? What outcomes might this research have in future? 

Nature of Science/Nature of Technology

  • What aspects of hurricanes are scientists actively researching? What outcomes might this research have in future? 

Media Literacy

  • What do meteorological reports tell us about emerging and active hurricanes? 

Media Literacy

  • What do meteorological reports tell us about emerging and active hurricanes? 

Teaching Suggestions

  • This article and embedded video can be used to support teaching and learning of Earth Science and Weather related to extreme weather, heat transfer, oceans and  wind. Concepts introduced include tropical cyclones, typhoons, hurricanes, evaporate, condenses, heat, ocean, eye of the storm, Coriolis Effect, tropical disturbance, tropical depression, tropical storm, tropical cyclone, Saffir-Simpson Scale, rainfall and storm surges. 

  • Before reading this article, teachers could have students complete a Vocabulary Preview learning strategy to access prior knowledge and introduce new terminology. Ready-to-use Vocabulary Preview reproducibles for this article are available in [Google doc] and [PDF] formats. 

  • To consolidate understanding of this topic, teachers could have students look at the similarities and differences between tropical cyclones with hurricanes by creating a Venn diagram to organize and compare the features of these weather phenomena.

  • After reading this article, teachers could have students consider the possible consequences of a hurricane or a tropical cyclone using a Consequence Mapping learning strategy. Ready-to-use Consequence mapping reproducibles for this article are available in [Google doc] and [PDF] formats. 

Teaching Suggestions

  • This article and embedded video can be used to support teaching and learning of Earth Science and Weather related to extreme weather, heat transfer, oceans and  wind. Concepts introduced include tropical cyclones, typhoons, hurricanes, evaporate, condenses, heat, ocean, eye of the storm, Coriolis Effect, tropical disturbance, tropical depression, tropical storm, tropical cyclone, Saffir-Simpson Scale, rainfall and storm surges. 

  • Before reading this article, teachers could have students complete a Vocabulary Preview learning strategy to access prior knowledge and introduce new terminology. Ready-to-use Vocabulary Preview reproducibles for this article are available in [Google doc] and [PDF] formats. 

  • To consolidate understanding of this topic, teachers could have students look at the similarities and differences between tropical cyclones with hurricanes by creating a Venn diagram to organize and compare the features of these weather phenomena.

  • After reading this article, teachers could have students consider the possible consequences of a hurricane or a tropical cyclone using a Consequence Mapping learning strategy. Ready-to-use Consequence mapping reproducibles for this article are available in [Google doc] and [PDF] formats. 

Learn more

The Coriolis Effect Explained (2018)

Video (2:43 min.) from Atlas Pro explaining how the Coriolis Effect causes tropical storms based on the rotation of the Earth.

These are all the hurricanes that hit Canada since 1900 (2017)

Information about all the major hurricanes that have impacted Canada since 1900 from Roberto Rocha at CBC News. Article includes interesting stats, graphics, and images.

Strongest Hurricanes: 10 Most Intense Atlantic Hurricanes on Record (2018) 

Weather.com's list of the most intense hurricanes that have occurred in the Atlantic, including the areas impacted, the damage caused, and some stats about the individual storms. 

Hurricanes and Climate Change 

Article by the Center for Climate and Energy Solutions discussing the relationship between hurricanes and climate change, outlining how hurricanes may become more intense as climate change progresses. Includes interesting map of all hurricanes tracked surrounding North America in 2015. 

References

Hurricanes: Science and Society. (2015). Aquatic impacts.

National Oceanic and Atmospheric Administration. (n.d.). Saffir-Simpson hurricane wind scale.

National Oceanic and Atmospheric Administration. (19, March 19). What is the difference between a hurricane and a typhoon?

SciJinks. (2019, June 27). How does a hurricane form?

University Corporation for Atmospheric Research. (2012). Hurricane impacts.