What are Typhoons? Dr. Badran Answers

 By Dr. Magdy Badran

Typhoons are one of the most dangerous natural hazards to people. Every year, they cause considerable loss of life and do immense damage to property. They last for about six days, in general, before they enter the land or reach subtropical latitudes. However, some can be detected only a few hours or perhaps a day or two, while others are observed as long as a fortnight.

Causes

Typhoons are caused by specific atmospheric and oceanic conditions that allow these intense tropical storms to develop.

Typhoons need sea surface temperatures of at least 26.5°C to form. Warm ocean waters heat the air above it, causing it to rise and create low-pressure areas that fuel the storm. This warmth is typically found in tropical and subtropical regions.

High humidity levels in the atmosphere provide energy for the storm. As warm, moist air rises, it cools and condenses, releasing latent heat, which powers the typhoon further.

The Coriolis effect, caused by Earth’s rotation, helps the storm develop a spinning motion. This effect is necessary to form the rotation of a typhoon and only becomes strong enough to influence weather systems significantly near the equator.

Wind shear refers to the change in wind speed or direction at different altitudes. Low wind shear allows the storm to grow vertically without being disrupted by different wind directions, which would otherwise weaken or distort the storm.

Typhoons thrive in unstable atmospheric conditions, where warm air near the ocean surface rises rapidly, leading to a cycle of updrafts and convection that sustains and intensifies the storm.

Many typhoons begin as tropical disturbances—clusters of thunderstorms that have already formed in the tropics. If these disturbances encounter the right conditions, they can develop into a tropical depression and eventually grow into a typhoon.

Globally, the average number of tropical cyclones (including typhoons, hurricanes, and cyclones, depending on the region) is about 80 to 90 per year.

Hazards

Winds in typhoons can exceed 150 km/h or even higher in severe cases. These winds can cause extensive damage, knocking down trees, power lines, and damaging buildings, especially in coastal areas which can cause injuries or fatalities. Typhoon Shanshan, peaked on August 28 with winds of up to 215 km/h. It struck Japan on August 29, leading to extensive evacuations and significant disruptions, including flight cancellations

Typhoons are often accompanied by intense rainfall that can lead flash flooding and river flooding that can drown people and destroy homes. Rainfall totals can be extremely high, especially if the typhoon moves slowly or stalls over a region.

The rapid rise of water levels due to the typhoon’s low pressure and strong winds can cause storm surges, which are large waves that push water inland. This can flood coastal areas, damage buildings, and endanger lives, especially in low-lying areas.

Intense rainfall can destabilize slopes and hillsides, leading to landslides. This is a particular risk in mountainous or hilly regions and can result in significant property damage, injury, and loss of life.

Typhoons can sometimes spawn tornadoes, particularly as they move inland. People may suffer injuries from falling objects, vehicle accidents during evacuation, or other related incidents.

Post-typhoon conditions, including contaminated water supplies and the spread of diseases, can lead to further health complications and deaths.

Difficulties in evacuating people safely can lead to overcrowding in shelters or delays in getting to safety, increasing the risk of casualties.

Essential services like electricity, water supply, transportation, and communication can be disrupted due to damaged infrastructure. This can delay emergency response and make recovery efforts challenging.

Climate change

Climate change is intensifying the characteristics and impacts of typhoons in several ways.

As global temperatures rise, ocean temperatures increase, providing more fuel for typhoons. Warmer waters lead to more powerful storms, which are capable of reaching higher categories with stronger winds and greater destructive potential.

A warmer atmosphere holds more moisture, which results in more intense rainfall during typhoons. This increases the risk of severe flooding, both from direct rainfall and from swollen rivers and water systems.

While the overall number of typhoons may not be increasing, the frequency of the most powerful typhoons has been rising. This means that when typhoons do occur, they’re more likely to be stronger and more dangerous.

Some studies suggest that climate change is slowing down the speed of typhoons, leading to more prolonged periods of heavy rain and strong winds over affected areas. This can result in severe flooding and prolonged damage.

Rising sea levels due to melting ice caps and thermal expansion make coastal areas more vulnerable to storm surges. Even moderate typhoons can cause severe flooding in areas where the sea level has risen, amplifying the impact on coastal communities.

Typhoons are now forming and reaching areas that were historically less affected, likely due to warmer ocean temperatures. For instance, places farther north or south of typical tropical storm zones may now experience typhoon impacts.

Deaths

The number of deaths caused by typhoons each year varies widely depending on factors like storm intensity, population density, preparedness, and response in affected regions. On average, tropical cyclones, including typhoons, can cause between 1,000 to 10,000 deaths globally per year. However, in some particularly severe years, fatalities have been much higher.

Typhoon Haiyan (2013) in the Philippines resulted in over 6,300 deaths. Typhoon Bopha (2012) caused around 1,900 deaths. In the Philippines.

The deadliest tropical cyclone in world history is the Great Bhola Cyclone, which struck Bangladesh in 1970 and caused approximately 500,000 fatalities. More recently, Cyclone Nargis, which made landfall in Myanmar in 2008, caused catastrophic destruction and at least 138,000 fatalities.

Fatalities are generally decreasing over time due to better forecasting, early warning systems, and improved infrastructure and response efforts. However, densely populated and vulnerable areas still face significant risk, especially as climate change contributes to more intense storms and flooding.

Typhoon Tips

While typhoons cannot be prevented, there are effective measures individuals and communities can take to reduce their impact and stay safe.

Stay Informed: Monitor weather updates and warnings through trusted sources like local news, weather apps, and government alerts to stay aware of any approaching typhoons.

Prepare an Emergency Kit: Assemble a kit with essentials such as food, water, medication, a flashlight, batteries, important documents, first-aid supplies, and emergency contact information.

Secure Your Home: Reinforce windows and doors, and trim tree branches near your house. Secure outdoor objects that could be picked up by strong winds.

Evacuate if Advised: If authorities recommend evacuation, do so promptly. Plan evacuation routes in advance and know where the nearest shelters are located.

Have a Family Communication Plan: Ensure all family members know where to meet or how to reach each other if separated.

Stock Up on Essentials: Gather extra food, water, and other supplies that can last at least 3-5 days in case of prolonged power outages or supply disruptions.

Turn Off Utilities if Necessary: In areas at high risk of flooding, consider turning off electricity, gas, and water before the typhoon hits.

Avoid Floodwaters: Do not walk or drive through floodwaters, as they can be deeper and more dangerous than they appear.

Prepare for Post-Storm Hazards: Hazards may remain after the typhoon passes, like downed power lines, fallen trees, and contaminated water. Follow official guidance on when it’s safe to move around.