Thunderstorms, Tornadoes, Lightning & Hailstorms

These flashcards cover the critical aspects of thunderstorms, tornadoes, lightning, and hailstorms as discussed in the lecture.

What atmospheric conditions initiate the cumulus stage of a thunderstorm?

Surface heating and convection cause moist air to rise, forming low-pressure and cumulonimbus clouds.

Why does the mature stage of a thunderstorm involve intense vertical growth?

Latent heat release during condensation reduces air density, fueling strong updrafts and vertical development.

How does a microburst differ from a macroburst in impact and scale?

Microbursts are smaller but can have wind speeds up to 270 km/h, causing localized but severe damage, especially to aircraft.

Why do thunderstorms tend to dissipate quickly after intense precipitation?

Downdrafts dominate, moisture is exhausted, and cold air cuts off updrafts, ending the convection cycle.

What makes orographic thunderstorms particularly hazardous in regions like Mawsynram or J&K?

Steep uplift of moist air against mountains causes localized, high-intensity rainfall and potential cloudbursts.

How do vertical wind shear and CAPE values influence thunderstorm severity?

Strong wind shear sustains updraft-tilt while high CAPE provides buoyant energy, together enhancing storm longevity and violence.

Why are multi-cell thunderstorms more unpredictable than single-cell systems?

Each cell interacts dynamically, leading to rapidly changing paths and potential for merging or splitting.

How do supercell thunderstorms differ structurally from ordinary storms?

They exhibit rotating mesocyclones, persistent updrafts, and tilted cores allowing prolonged severe weather.

Why do thunderstorms often form along dry lines in semi-arid regions?

Sharp moisture contrast between dry and moist air masses triggers rapid convection at the boundary.

How does a squall line develop and what hazards does it pose?

It forms along advancing cold fronts and produces linear storms with strong winds, heavy rain, and embedded tornadoes.

What causes charge separation within a cumulonimbus cloud?

Collision between ice particles, graupel, and water droplets causes differential charging with positive tops and negative bases.

Why does cloud-to-ground lightning favor negatively charged strokes?

Negatively charged base seeks ground's positive charge, discharging through stepped leaders and return strokes.

How does upward lightning occur from tall structures?

Strong electric fields near the tips trigger upward positive streamers toward negatively charged clouds.

Why are lightning fatalities high in tropical countries like India?

Frequent convection, outdoor labor-intensive occupations, and inadequate early warning raise vulnerability.

What role does ELF radiation play in tracking global lightning activity?

Very low frequency emissions from lightning can be monitored globally to detect thunderstorm hotspots.

How do tornadoes originate from mesocyclones within supercells?

Low-level wind shear and rotating updrafts tighten into a vortex under the cloud base, extending to the ground.

Why are tornadoes more frequent in Tornado Alley than elsewhere?

Convergence of warm moist Gulf air, dry air from Rockies, and cool northern air creates ideal vertical shear.

How do landspouts and waterspouts differ from classic tornadoes?

They form without mesocyclones, are weaker, and arise from surface vorticity rather than mid-level rotation.

What makes multiple-vortex tornadoes especially destructive?

Several subvortices orbit a common center, each capable of severe localized damage.

Why are Doppler radars critical for tornado detection?

They detect rotation (velocity couplets) within storms before funnels reach the surface, enabling early alerts.

Why is strong updraft critical for hailstone growth?

It suspends growing ice particles long enough for repeated accretion of supercooled water.

How do concentric layering patterns form in large hailstones?

Repeated lifting and freezing in updrafts alternates between wet and dry growth phases.

Why do hailstorms often accompany high CAPE but low freezing level?

High CAPE supports strong updrafts; low freezing level keeps hailstones frozen before they hit the ground.

Where in India are hailstorms most frequent and why?

Vidarbha, Chhattisgarh, and NE India due to spring convection and proximity to convergence zones.

How does wet growth differ from dry growth in hailstone formation?

Wet growth involves rapid accretion and trapping of liquid water; dry growth has slower ice layering with air pockets.

Why are thunderstorm days highest over equatorial Africa?

High insolation, moisture availability, and terrain-induced convection maximize daily storm activity.

How does El Niño suppress thunderstorm activity in South Asia?

Warmer Pacific weakens monsoon circulation and vertical instability, reducing thunderstorm frequency.

Why is nocturnal thunderstorm development common in certain regions?

Residual boundary layer instability and low-level jets sustain uplift during early night hours.

How do terrain features like the Ghats influence thunderstorm distribution?

Orograhphic uplift enhances convective potential on windward slopes, triggering storms during pre-monsoon.

What makes urban regions vulnerable to intense convective storms?

Urban heat islands and aerosol loading enhance local uplift and microphysical changes in storm clouds.

How might climate change intensify thunderstorm hazards?

Warming increases atmospheric moisture and CAPE, potentially enhancing storm intensity and rainfall rates.

Why are hailstorm events becoming more spatially erratic?

Changing jet streams and regional thermal profiles disrupt traditional hail-prone zones.

How does increased aerosol concentration affect lightning activity?

More cloud condensation nuclei enhance droplet coalescence and electrification, increasing lightning frequency.

Why are compound hazards from thunderstorms rising globally?

Intense rain, flash floods, hail, and wind occur simultaneously, overwhelming response systems.

How does thunderstorm electrification vary with altitude and geography?

Tropics see high-altitude storms with upper charge layers; mid-latitudes have stronger mid-level electrification.

What conditions lead to Nor’westers (Kalbaisakhi) in eastern India?

Pre-monsoon heating and moisture influx from Bay of Bengal create convective instability and gusty squalls.

How does the IMD classify severe thunderstorm alerts?

Based on wind speed, rainfall, lightning, and potential for hail or tornado formation using Doppler radar inputs.

Why is March-May the peak season for thunderstorms in peninsular India?

Increasing surface temperatures and transition in wind regimes enhance convective potential.

How does wind shear over Deccan Plateau influence storm duration?

Moderate shear tilts updrafts, sustaining storm structure without choking inflow.

Which agro-climatic zones in India face maximum crop damage from hailstorms?

Vidarbha, Bundelkhand, and parts of Uttarakhand during rabi harvesting season.

How does satellite-based lightning imaging help in storm forecasting?

It detects high-frequency lightning bursts which indicate strong updrafts and imminent severe weather.

What role do nowcasting systems play in minimizing thunderstorm impacts?

Short-term radar and satellite inputs allow rapid warnings with 30–60 min lead times.

How can vertical thermodynamic profiling predict hail potential?

Temperature and moisture sounding shows CAPE, freezing level, and lapse rate critical for hail forecasting.

Why are cloudbursts considered extreme thunderstorm variants?

They involve short-duration rainfall >100 mm/hour due to orographic trapping and saturated uplift.

What strategies are used for crop protection against hailstorm damage?

Use of anti-hail nets, real-time alerts, and contingency cropping reduce risk and economic loss.

Why are mid-level convergence zones key for initiating mesoscale convective systems?

They bring together moist lower layers and unstable middle troposphere, triggering sustained convection.

How do elevated thunderstorms differ from surface-based ones in origin and hazard?

They initiate above a stable boundary layer and may produce intense hail and lightning despite weak surface signals.

What distinguishes positive lightning strikes from negative ones in terms of damage potential?

Positive lightning carries higher voltage and longer duration, capable of greater destruction and igniting wildfires.

How can thermodynamic indices like Lifted Index and K-Index forecast thunderstorm risk?

Negative Lifted Index and high K-Index indicate strong instability and moisture, favoring convective activity.

Why is hail forecasting more uncertain than rainfall forecasting?

Hail formation depends on microphysical processes within clouds, updraft strength, and freezing levels, which are hard to model accurately.