Ch 10 Quiz: Tropical Meteorology — ITCZ, Monsoon & Cyclones

ITCZ: near-equatorial belt of low pressure where NH and SH trade winds converge. Rising motion produces towering Cbs, heavy rainfall, and thunderstorms. Migrates seasonally with the overhead sun.

Persistent subsidence and clear skies

Correct Incorrect Correct answer

A band of convergence, convection, and deep Cb activity near the equator where the trade winds meet

Correct Incorrect Correct answer

Jet stream activity

Correct Incorrect Correct answer

Cold frontal passage

Correct Incorrect Correct answer

Asian SW Monsoon: intense summer heating of Asia creates a thermal low, drawing moist maritime air from the Indian Ocean inland with heavy rainfall June-September. Winter: land cools, high pressure develops, dry winds flow seaward.

Ocean currents alone

Correct Incorrect Correct answer

Differential heating between land and ocean — summer SW monsoon: low pressure over hot Asian landmass draws moist maritime air inland

Correct Incorrect Correct answer

Polar front activity

Correct Incorrect Correct answer

ITCZ migration only

Correct Incorrect Correct answer

Tropical cyclone formation requires SST ≥ 26-27C to provide sufficient latent heat flux to sustain the warm core. Below this threshold, surface fluxes are insufficient to maintain the cyclone’s energy.

25C

Correct Incorrect Correct answer

26.5C (approximately)

Correct Incorrect Correct answer

30C

Correct Incorrect Correct answer

20C

Correct Incorrect Correct answer

Cyclones rotate anti-clockwise in the NH and clockwise in the SH, due to Coriolis deflection.

Clockwise

Correct Incorrect Correct answer

Anti-clockwise (cyclonic in NH)

Correct Incorrect Correct answer

Randomly

Correct Incorrect Correct answer

Clockwise below 15N only

Correct Incorrect Correct answer

The eye: calm, warm, clear centre, 20-60 km diameter. Sinking air produces warmth and calm. The EYEWALL just outside has most violent winds, tallest Cbs, heaviest rain, and extreme turbulence.

Heaviest rain and strongest winds

Correct Incorrect Correct answer

Relatively calm, warm, cloud-free centre — surrounded by the eyewall with extreme winds

Correct Incorrect Correct answer

Cold temperatures and descending air

Correct Incorrect Correct answer

Jet stream activity

Correct Incorrect Correct answer

Saffir-Simpson: Cat 1 (64-82 kt), Cat 2 (83-95 kt), Cat 3 (96-112 kt — major), Cat 4 (113-136 kt), Cat 5 (≥137 kt). Based on 1-minute sustained winds.

Diameter of the eye

Correct Incorrect Correct answer

Maximum sustained wind speed — Category 1 (64-82 kt) to Category 5 (≥ 137 kt)

Correct Incorrect Correct answer

Central pressure alone

Correct Incorrect Correct answer

Wave height

Correct Incorrect Correct answer

Regional names: Atlantic/E. Pacific = Hurricane; W. Pacific = Typhoon; Indian Ocean/Bay of Bengal/Arabian Sea = Cyclone; Australia = Willy-Willy.

Typhoons

Correct Incorrect Correct answer

Cyclones (Indian Ocean cyclone)

Correct Incorrect Correct answer

Hurricanes

Correct Incorrect Correct answer

Willy-Willies

Correct Incorrect Correct answer

Tropical cyclone SIGMETs: issued when sustained surface winds reach or are expected to reach ≥ 34 kt. Include position, movement, central pressure, and maximum winds.

34 kt or more

Correct Incorrect Correct answer

≥ 34 kt (Beaufort 8) — tropical storm threshold requiring SIGMETs

Correct Incorrect Correct answer

≥ 64 kt

Correct Incorrect Correct answer

Any tropical depression

Correct Incorrect Correct answer

The eyewall contains the highest winds, most extreme turbulence, heaviest precipitation, and most severe icing. Most dangerous part of a tropical cyclone for aviation.

In the eye

Correct Incorrect Correct answer

In the outer rain bands

Correct Incorrect Correct answer

In the eyewall — the ring of tallest Cbs surrounding the eye

Correct Incorrect Correct answer

On the equatorial side

Correct Incorrect Correct answer

In the tropics, Coriolis is weak (zero at equator). No mid-latitude fronts. Weather dominated by: ITCZ, trade winds, easterly waves, convection, and monsoon circulations.

There are no fronts

Correct Incorrect Correct answer

Coriolis force is zero at the equator, so fronts and balanced geostrophic flow do not form — weather is driven by convection and the ITCZ

Correct Incorrect Correct answer

Trade winds are always calm

Correct Incorrect Correct answer

Thunderstorms do not occur

Correct Incorrect Correct answer

Easterly wave: westward-moving wave in trade winds, wavelength ~2500 km. Convergence behind trough axis → active convection. Seed for tropical cyclone development.

A jet stream oscillation

Correct Incorrect Correct answer

A wavelike disturbance in the tropical easterly trade wind belt — an inverted trough that moves westward and may develop into a tropical cyclone

Correct Incorrect Correct answer

A katabatic wind system

Correct Incorrect Correct answer

A polar front feature

Correct Incorrect Correct answer

Dry season: ITCZ migrates to opposite hemisphere. Region comes under subtropical high (subsidence, stable air, suppressed convection → dry weather).

ITCZ overhead

Correct Incorrect Correct answer

Subsidence from the Hadley cell — trade wind belt under the descending limb, suppressing convection

Correct Incorrect Correct answer

Monsoon onset

Correct Incorrect Correct answer

Easterly wave activity

Correct Incorrect Correct answer

Tropical CAPE: typically 3000-5000 J/kg vs 1000-2500 J/kg in mid-latitudes. Produces towering Cbs reaching 60000 ft, intense rainfall rates, and severe turbulence.

Lower than mid-latitudes

Correct Incorrect Correct answer

Higher than mid-latitudes (often 3000-5000 J/kg), allowing very deep convection

Correct Incorrect Correct answer

The same

Correct Incorrect Correct answer

Near zero

Correct Incorrect Correct answer

MJO: dominant mode of tropical intra-seasonal variability. Cluster of enhanced convection moves eastward around tropics every 30-90 days. Modulates tropical cyclone activity and Asian monsoon.

A jet stream oscillation

Correct Incorrect Correct answer

An eastward-moving planetary wave of enhanced and suppressed convection in the tropics with a period of 30-90 days

Correct Incorrect Correct answer

A type of tropical cyclone

Correct Incorrect Correct answer

An ocean current

Correct Incorrect Correct answer

ITF/monsoon trough: boundary between dry Harmattan/continental air and moist onshore monsoon air. Unlike polar fronts, it is a MOISTURE (humidity) discontinuity rather than a sharp temperature contrast.

A mid-latitude front

Correct Incorrect Correct answer

The boundary between the dry continental air and the moist monsoon air in tropical Africa and South Asia — a moisture discontinuity, not a temperature front

Correct Incorrect Correct answer

The ITCZ over oceans

Correct Incorrect Correct answer

A squall line front

Correct Incorrect Correct answer

IMD classification: Depression (17-27 kt), Deep Depression (28-33 kt), Cyclonic Storm (34-47 kt), Severe Cyclonic Storm (48-63 kt), Very Severe (64-89 kt), Extremely Severe (90-119 kt), Super Cyclonic Storm (≥120 kt).

34-47 kt

Correct Incorrect Correct answer

48-63 kt — IMD Severe Cyclonic Storm (SCS)

Correct Incorrect Correct answer

64-89 kt

Correct Incorrect Correct answer

< 33 kt

Correct Incorrect Correct answer

Cyclone weakening at landfall: loss of warm ocean moisture supply, increased surface friction, colder drier land surface. Weakening can be rapid (12-24 hours).

Temperature drops immediately

Correct Incorrect Correct answer

The energy source (warm ocean evaporation/latent heat) is cut off over land, and increased surface friction disrupts the circulation

Correct Incorrect Correct answer

Coriolis increases

Correct Incorrect Correct answer

Pressure increases

Correct Incorrect Correct answer

Tropical cyclone SIGMETs: issued by MWOs when sustained surface winds ≥ 34 kt within or expected within the FIR. Include position, movement, central pressure, maximum winds.

A depression forms anywhere

Correct Incorrect Correct answer

The system has sustained surface winds ≥ 34 kt (tropical storm intensity) within the FIR

Correct Incorrect Correct answer

A Category 5 only

Correct Incorrect Correct answer

Always, even for depressions

Correct Incorrect Correct answer

Tropical depression: organised convective system with closed circulation and sustained surface winds 17-33 kt. May intensify into a cyclonic storm if SST and atmospheric conditions are favourable.

< 17 kt

Correct Incorrect Correct answer

17-33 kt

Correct Incorrect Correct answer

34-47 kt

Correct Incorrect Correct answer

48-63 kt

Correct Incorrect Correct answer

Pre-monsoon India: intense surface heating builds CAPE. Bengal: Kalbaisakhi (Nor’westers). NW India: dust storms (andhi). SW India: pre-monsoon heat, isolated convection.

Cold clear weather

Correct Incorrect Correct answer

High CAPE, pre-monsoon thunderstorms (Kalbaisakhi/Nor'westers in Bengal, dust storms in NW India), hot and humid conditions building toward monsoon onset

Correct Incorrect Correct answer

Heavy continuous rain

Correct Incorrect Correct answer

Polar air intrusion

Correct Incorrect Correct answer

SW monsoon onset over Kerala: traditionally around June 1 (±7 days). Progresses NE across India, reaching Delhi around July 1.

October

Correct Incorrect Correct answer

June 1 (+/- 7 days) — onset of monsoon over Kerala marks the official beginning of the SW monsoon season

Correct Incorrect Correct answer

August

Correct Incorrect Correct answer

March

Correct Incorrect Correct answer

North Indian Ocean cyclone seasons: Bay of Bengal peaks October-December (post-monsoon) and May-June (pre-monsoon). Monsoon season (July-September) suppresses cyclone formation due to strong vertical wind shear.

January-February

Correct Incorrect Correct answer

Pre-monsoon (April-June) and post-monsoon (October-December) — the main seasons

Correct Incorrect Correct answer

July-August (monsoon)

Correct Incorrect Correct answer

Year-round equally

Correct Incorrect Correct answer

Kalbaisakhi: pre-monsoon convective storms in Bengal. Strong convection driven by hot NW continental air meeting moist SE Bay of Bengal flow → Cbs, squalls, hail, and lightning.

Gentle rain

Correct Incorrect Correct answer

Intense squalls and thunderstorms developing from the NW in late afternoon/evening during pre-monsoon

Correct Incorrect Correct answer

Fog development

Correct Incorrect Correct answer

Tropical cyclone activity

Correct Incorrect Correct answer

Break monsoon: 7-14 day period of weakened monsoon activity over central/peninsular India when the trough shifts northward to the Himalayan foothills.

End of monsoon season

Correct Incorrect Correct answer

A period when rainfall over the Gangetic Plain temporarily ceases as the monsoon trough shifts to the Himalayas

Correct Incorrect Correct answer

Start of monsoon

Correct Incorrect Correct answer

Post-monsoon NE monsoon

Correct Incorrect Correct answer

ITCZ double ITCZ: split into two parallel zones, one N and one S of the equator. More common in the E Pacific. Individual bands can spawn easterly waves and tropical cyclone development.

No meteorological significance

Correct Incorrect Correct answer

The ITCZ splits into two separate convergence zones — one in each hemisphere near the equator

Correct Incorrect Correct answer

Temperature drops rapidly

Correct Incorrect Correct answer

Trade winds weaken to zero

Correct Incorrect Correct answer

Monsoon withdrawal: begins NW India (Rajasthan) around September 1, progresses S and E, completing over SE India by late November.

July

Correct Incorrect Correct answer

September — withdrawal from NW Rajasthan around September 1, complete over all India by end of November

Correct Incorrect Correct answer

May

Correct Incorrect Correct answer

January

Correct Incorrect Correct answer

Tropical Cb tops: tropical tropopause at ~16-18 km (FL520-590) allows convection to grow much taller than in mid-latitudes (~10-12 km). Tropical Cbs can reach FL500-560.

FL150

Correct Incorrect Correct answer

FL500-FL550 (16-18 km) — tropical tropopause much higher than mid-latitudes

Correct Incorrect Correct answer

FL250

Correct Incorrect Correct answer

FL350

Correct Incorrect Correct answer

Bay of Bengal monsoon depressions: track WNW along the monsoon trough, making landfall over the E coast of India and moving into central India, causing widespread flooding.

Eastward to Southeast Asia

Correct Incorrect Correct answer

West-northwest along the monsoon trough, across Odisha/Andhra Pradesh into central India — bringing widespread heavy rainfall

Correct Incorrect Correct answer

Northward to Nepal

Correct Incorrect Correct answer

Southward to Sri Lanka

Correct Incorrect Correct answer

IOD and ENSO affect Indian monsoon: positive IOD (warm W Indian Ocean) enhances monsoon. El Nino typically weakens Indian monsoon. La Nina enhances it.

Tsunami prediction

Correct Incorrect Correct answer

ENSO and Indian Ocean Dipole effects on monsoon strength — warm/cold SST anomalies modulate interannual monsoon variability

Correct Incorrect Correct answer

Flight level forecasting

Correct Incorrect Correct answer

Upper-level winds only

Correct Incorrect Correct answer

Thar Desert thermal low: intense summer heating creates a surface thermal low. Combined with Tibetan Plateau heating, creates strong pressure gradient drawing moist SW monsoon air inland.

It has no meteorological significance

Correct Incorrect Correct answer

It draws in moist SW air from the Arabian Sea — a key mechanism sustaining the Indian Summer Monsoon

Correct Incorrect Correct answer

It causes tropical cyclones

Correct Incorrect Correct answer

It creates a jet stream

Correct Incorrect Correct answer

Ch 10 Quiz: Tropical Meteorology — ITCZ, Monsoon & Cyclones

Quiz Summary

Information

Results

Results

Categories

1. Question

2. Question

3. Question

4. Question

5. Question

6. Question

7. Question

8. Question

9. Question

10. Question

11. Question

12. Question

13. Question

14. Question

15. Question

16. Question

17. Question

18. Question

19. Question

20. Question

21. Question

22. Question

23. Question

24. Question

25. Question

26. Question

27. Question

28. Question

29. Question

30. Question

Company

Legal

Connect