Why In News?

Typhoon Dolphin, this year's strongest tropical cyclone in China, made landfall in Zhejiang province, causing over one million people to be evacuated.

 

What is a Typhoon?

A typhoon is a tropical cyclone that forms over the northwestern Pacific Ocean, the regional term equivalent to "hurricane" (Atlantic/NE Pacific) and "cyclone" (South Pacific/Indian Ocean) — classification is region-specific, not structurally different.

 

 

 

 

Formation conditions 

Oceanic Requirements

  • Sea Surface Temperature: Ocean waters must reach at least 26.5°C to supply the necessary energy.

  • Ocean Thermal Depth: This warm water layer must extend down to a depth of roughly 50 meters to prevent the storm's waves from churning up cooler water from below.

 

Atmospheric Requirements

  • Low Vertical Wind Shear: Weak winds aloft are required. Strong, changing winds at high altitudes will rip the vertical structure of the developing typhoon apart.

  • High Mid-Tropospheric Humidity: Abundant moisture in the middle levels of the atmosphere is necessary to sustain cloud formation and thunderstorm activity.

  • Atmospheric Instability: The air must cool rapidly with height, allowing the warm, moist ocean air to rise rapidly, condense, and release latent heat.

  • Pre-existing Disturbance: A seed disturbance, such as a low-pressure area or an easterly wave, must be present to initiate organized thunderstorm activity.

 

Planetary Dynamics

  • Coriolis Force: The disturbance must be located at least 5° latitude away from the Equator (North or South). The Coriolis effect is too weak at the equator to create the spinning motion required to form a closed cyclonic vortex.

 

Why is China Vulnerable to Typhoons?

  • Long coastline: China has one of the world's longest coastlines, directly exposed to the NW Pacific typhoon belt.

  • Dense coastal population: Provinces like Zhejiang, Jiangsu, Fujian, and cities like Shanghai concentrate a disproportionate share of China's population and GDP along the coast.

  • Multiple storms per season: Typhoon Co-May, which made landfall in Zhejiang in 2025, was the eighth typhoon of that year to hit the country— indicating high storm frequency compounding cumulative risk.

  • Rapid urbanisation: Expansion of impervious surfaces (concrete, roads) in coastal cities increases flash-flood risk during heavy rainfall events.

  • Climate Change: Global warming has made extreme weather more likely, including stronger typhoons. Combination of sea-level rise and stronger storm surge amplifies coastal flooding risk in low-lying delta cities like Shanghai.

 

Source: THEHINDU

 

 

 

PRACTICE QUESTION

Q1. With reference to Typhoon Dolphin (2026), consider the following statements:

  1. It made landfall in Zhejiang province on the eastern coast of China.

  2. It formed over the northwestern Pacific Ocean.

  3. Its wind speed at landfall was equivalent to a Category 3 hurricane on the Saffir-Simpson scale.

Which of the statements given above is/are correct? 

(a) 1 and 2 only 

(b) 2 and 3 only 

(c) 1 only 

(d) 1, 2 and 3

Answer: (a)

Explanation:

Statement 1 is correct: Typhoon Dolphin made landfall near Yuhuan in Zhejiang province on the eastern coast of China on Sunday, 9 August 2026. 

Statement 2 is correct: Typhoon Dolphin formed over the northwestern Pacific Ocean (west of the International Date Line) and tracked across a long distance toward the East China Sea.  

Statement 3 is incorrect: At landfall, Typhoon Dolphin packed maximum sustained winds of approximately 151 km/h (94 mph or 42 m/s). On the Saffir-Simpson scale, winds between 119–153 km/h (74–95 mph) are classified as a Category 1 hurricane, not a Category 3 hurricane.