What Is a Tropical Cyclone?

Tropical cyclones are one of the most dangerous weather hazards. Tropical cyclones begin in tropical waters and can bring winds up to 180 mph along with extreme rain, waves, storm surges, and coastal flooding. The World Meteorological Association attributes tropical cyclones to 1,942 disasters over the last 50 years, killing 779,324 people and leading to over $1.4 trillion of damages.

What's a tropical cyclone?

"Tropical cyclone" describes any non-frontal large-scale low-pressure system that develops over warm tropical waters and lasts for at least six hours. These form when the surface temperature of the sea rises above 78.8°F.

Hurricanes, tropical storms, typhoons, tropical depressions, or simply cyclones—these terms are often used interchangeably. From a technical standpoint, rotating storms are categorized based on their intensity and where they are formed. The National Oceanic and Atmospheric Administration or NOAA uses the following classification for tropical cyclones:

Tropical cyclones with wind speeds under 74 mph:

1. Tropical depression: A tropical cyclone with sustained surface winds (winds blowing close to the earth's surface) below 39 mph.
2. Tropical storm: A tropical cyclone with wind speeds over 39 mph.

Tropical cyclones with wind speeds over 74 mph are named based on where they're formed:

1. Cyclone: South Pacific and Indian Ocean.
2. Hurricane: North Atlantic Ocean and Northeast Pacific.
3. Typhoon: Northwest Pacific Ocean

What causes tropical cyclones?

Warm moist air in tropical ocean waters rise and cause a low pressure area to form. Higher pressure air pushes into this lower pressure zone resulting in a swirling effect as the "newer" air comes in to take the place of the "older" air.

As the warm air ascends further, it cools off and condenses, causing clouds to form. This cycle of high-pressure air being replaced by warm low-pressure air, the subsequent surface evaporation, the eventual cooling off, and condensation feeds the compact combination of clouds and wind, making it grow more and spin faster. This develops into a storm system that rotates faster and faster. Although most of the air flows upwards and outwards, some of it flows towards the inner part of the storm. This builds up air pressure further, reaching the point where the weight of the air cancels out the strength of the rising air. When this happens, the higher-pressure air weakens and starts to sink towards the system's center, which creates the "eye of the storm." If the environmental conditions are right, tropical cyclones can keep their structure intact, allowing them to persist or even intensify over the next few days.

What can be done?

Before the storm

Although we can't stop a tropical cyclone once it starts forming, there's much we can do to mitigate disaster risk. If you live in high-risk areas, here are a few ways by which you can protect yourself and your loved ones from the impact of cyclones.

Typically, hurricane or cyclone season begins in mid-May in the North Pacific, while it occurs in June in the Atlantic and the Caribbean. During this time, the National Weather Service provides forecasts and issues the necessary watches and warnings for any weather disturbance, including tropical storms. Monitoring the weather forecasts is highly encouraged, so you can have time to prepare and evacuate before the cyclone hits your area.

Beforehand, make sure you have all the emergency phone numbers. Post this information in prominent areas such as on your refrigerator door. An emergency kit containing a flashlight, battery-powered radios (in case of power outages), medical supplies (including a two-week prescription supply), extra batteries, disinfectant wipes, a waterproof folder with your essential documents, gas for your car, matches, a fire extinguisher, and a first-aid kit. Of course, bring enough cash, food, and water to last you for at least two weeks.

Plan ahead and check for shelters where you and your family and friends may take emergency shelter. Be mindful of the needs of your young children and elderly relatives who will find it difficult to evacuate in haste. Don't forget to also plan for your pets.

After the storm

Stay away from flooded areas and never drive through floodwater, which may contain broken glass, downed electric cables, hazardous human and chemical wastes, and even animals that have rabies or venom.

In the absence of electricity, people turn to fuel-burning equipment. However, this releases carbon monoxide into the air. To prevent CO poisoning, check if your CO detector is still working. Generators should be outside your home, at least 20 feet away from doors, windows, or similar outlets.

Final Thoughts

Climate change data reveals that global warming strengthens hurricanes, increasing the chances of Category 3 storms or higher. Thus, governments and institutions are working together to develop a more effective sustainability strategy that tackles climate risk, which includes disaster risk management. Understanding your property's risk to climate change and cyclones by staying well-informed and cooperating with government authorities can help us protect ourselves, our families, and our communities from the loss of life and property.