Comparison between temperate and tropical cyclones

At first glance, both tropical and temperate cyclones appear similar — low-pressure systems with strong winds and rainfall.
But their origin, structure, dynamics, and impacts are very different.

Tropical vs Temperate Cyclones

1. Origin

• Tropical Cyclones → Thermal origin. Powered mainly by latent heat of condensation.
• Temperate Cyclones → Dynamic origin. Caused by frontogenesis — interaction of contrasting warm and cold air masses, along with Coriolis force.

👉 Think of tropical cyclones as “heat engines” and temperate cyclones as “battlefields of air masses.”

2. Latitude Range

• Tropical: 10°–30° N/S (closer to equator, but not right at the equator due to weak Coriolis force).
• Temperate: 35°–65° N/S (mid-latitudes, polar front zone).
• More frequent in Northern Hemisphere due to stronger land–sea temperature contrasts.

3. Frontal System

• Tropical: No fronts → air mass is uniform.
• Temperate: Defined by frontogenesis (warm front, cold front, occluded front).

4. Formation Environment

• Tropical: Requires sea surface temperature > 26–27°C. Dies after landfall (no moisture supply).
• Temperate: Can form on both land and sea, survives longer due to continuous air mass contrasts.

5. Seasonality

• Tropical: Seasonal → peak in late summers (Aug–Nov).
• Temperate: Irregular, but more frequent in winters.

6. Size

• Tropical: Smaller — typically 100–500 km wide.
• Temperate: Larger — 300–2000 km wide.

7. Shape

• Tropical: Nearly elliptical/circular.
• Temperate: Inverted “V” or comma-shaped.

8. Rainfall

• Tropical: Intense, heavy downpour; short duration (hours to a couple of days).
• Temperate: Lighter but long-lasting; continuous drizzle/rain for days or even weeks.

9. Wind Velocity & Damage

• Tropical: Stronger → 100–250 km/h at surface; destructive due to winds + storm surge + torrential rains.
• Temperate: Moderate → 30–150 km/h; damage mainly from flooding, snowstorms, cold waves.

10. Isobars & Pressure Gradient

• Tropical: Isobars are circular, closely packed → steep pressure gradient.
• Temperate: Isobars are V-shaped → gentle pressure gradient.

11. Lifetime

• Tropical: Short → rarely more than a week.
• Temperate: Longer → 2–3 weeks.

12. Path of Movement

• Tropical: East → West, then curve northward at ~20° and turn eastward at ~30°.
• Temperate: West → East (driven by westerlies & jet streams).

13. Temperature Distribution

• Tropical: Almost uniform (no contrasting air masses).
• Temperate: Clear contrast → warm, cold, and occluded sectors.

14. Calm Region

• Tropical: Has an eye — calm, rainless zone in centre.
• Temperate: No calm centre; entire system is turbulent.

15. Driving Force

• Tropical: Powered by latent heat of condensation.
• Temperate: Powered by temperature & density contrasts of air masses.

16. Influence of Jet Streams

• Tropical: Relationship unclear, though upper-level winds can aid/impede intensity.
• Temperate: Strongly linked with jet streams & Rossby waves.

17. Cloud Types

• Tropical: Limited → mainly cumulonimbus, nimbostratus.
• Temperate: Wide variety at different levels → cirrus, stratus, cumulonimbus, altostratus, etc.

18. Anticyclone Association

• Tropical: Not associated with surface anticyclones → greater destructive potential.
• Temperate: Usually preceded and followed by anticyclones, making them less destructive.

19. Impact on India

• Tropical: Both coasts affected (especially East coast — Bay of Bengal is hotspot).
• Temperate: Enter NW India as Western Disturbances → crucial for winter rains.

20. Predictability

• Tropical: Movement is erratic due to multiple influencing factors.
• Temperate: Path more predictable due to westerly flow and frontal mechanics.

✅ Summary for UPSC

Aspect	Tropical Cyclone	Temperate Cyclone
Origin	Thermal (latent heat)	Dynamic (air mass contrasts)
Latitude	10°–30°	35°–65°
Fronts	Absent	Present (frontogenesis)
Size	100–500 km	300–2000 km
Shape	Circular/Elliptical	Inverted “V”
Rainfall	Heavy, short duration	Light, long duration
Winds	100–250 km/h	30–150 km/h
Calm Centre	Eye present	No calm zone
Lifetime	≤ 1 week	2–3 weeks
Path	East → West → North turn	West → East
India	Affects coasts	Western Disturbances

👉 In short: Tropical cyclones are intense but short-lived thermal systems, while temperate cyclones are large, long-lived dynamic systems that dominate mid-latitudes.