Characteristics of Tropical Cyclones

General Characteristics

When we talk about cyclones, we usually divide them into two big categories:

• Temperate or Extratropical Cyclones → Found in mid-latitudes.
• Tropical Cyclones → Born between the Tropics of Cancer and Capricorn.

Here, we focus on tropical cyclones. Unlike their temperate counterparts, they are not uniform or regular. Their size, shape, intensity, and impact differ greatly. But still, some general characteristics help us identify them. Let’s go through these one by one.

1. Size Variation

• Tropical cyclones are not all massive monsters.
• On average, their diameter ranges from 80 km to 300 km.
• Sometimes they are so small that their spread is less than 50 km — imagine a storm covering just a city!
  👉 The takeaway: size is not fixed; it depends on local conditions.

2. Velocity of Movement

• Weak cyclones crawl forward at around 32 km/h.
• But when they intensify into hurricanes or typhoons, their speed can shoot up to 180 km/h or more.
  👉 This means some cyclones are slow and lingering, while others rush like a high-speed train.

3. Strength Over Sea, Weakness Over Land

• Over the ocean, cyclones thrive because they draw their energy from warm, moist air.
• But as soon as they hit land, they weaken — no more moisture to fuel them.
• That’s why the coastal regions are most vulnerable (examples: US south-east coast, Tamil Nadu, Odisha, West Bengal, southern Bangladesh).
  👉 Cyclones are like a “sea creature” — strong in water, weak on land 😊

4. The Eye – Extremely Low Pressure

• At the centre (the eye), the pressure is extremely low.
• The isobars (lines connecting equal pressure) are circular and sparse, showing a rapid fall in pressure.
• Winds rush towards this centre at gale force.
  👉 This is why the eye wall (around the eye) has the strongest winds and heaviest rainfall.

5. No Temperature Contrasts (No Fronts)

• In temperate cyclones, we see warm and cold fronts → different air masses clashing.
• But in tropical cyclones, there are no such fronts.
• Hence, no major temperature variations inside different parts of the cyclone.
  👉 The cyclone is more uniform in its thermal nature.

6. Uniform Rainfall

• In temperate cyclones, rainfall happens in distinct cells (frontal rainfall zones).
• But here, rainfall can occur in all parts of the cyclone.
  👉 That’s why even if you are not near the cyclone’s centre, you may still face heavy rains.

7. Not Always Moving

• Some cyclones remain stationary for days, dumping rainfall continuously.
• This leads to floods and environmental disasters.
  👉 A moving cyclone is dangerous, but a stationary one is even more disastrous.

8. Tracks and Path

• Cyclones follow a general path influenced by trade winds:
  • East → West up to about 15° latitude.
  • Turn Poleward between 15°–30°.
  • Beyond that, again westerly movement.
• Once they move into subtropical regions, they weaken.
  👉 This explains why India’s east coast is hit more often than the west coast.

9. Seasonality

• They are seasonal, usually occurring in the summer when oceans are warm.
• Their frequency is much lower compared to temperate cyclones.
  👉 For India, peak season is post-monsoon (October–November) and also pre-monsoon (May–June).

10. Natural Hazards – Why They Are Disastrous

Tropical cyclones are among the most dangerous natural disasters because of:

• High wind speeds (180–400 km/h).
• Storm surges (sea water rises abnormally, flooding coasts).
• Heavy rainfall (Philippines once recorded >2000 mm in a single day).
• Very low pressure, which raises sea level.
• Long duration, sometimes persisting for a week in one region.

👉 In short, tropical cyclones are a package of hazards — winds, rain, floods, and tidal waves.

✅ Summary for UPSC:

• Tropical cyclones = seasonal, ocean-based, low-pressure systems.
• They weaken on land but devastate coastal regions.
• No fronts, no temperature contrasts, but massive rainfall and wind.
• Their paths and timings are predictable, but their impact is often catastrophic.