During a thunderstorm, the thunder in the skies is produced by the 1. Meeting of cumulonimbus clouds in the sky. 2. Lightning that separates the nimbus clouds. 3. Violent upward movement of air and water particles. Select the correct answer using the codes given below:
Contents14
- A1 only
- B2 and 3
- C1 and 3
- DNone of the above produces the thunder
Show answer
Answer: (D) None of the above produces the thunder
None of the three given statements correctly explains what produces thunder.
Thunder is actually the sound caused by lightning.
When lightning strikes, there is a sudden massive increase in pressure and temperature, which causes the air surrounding the lightning bolt to expand extremely rapidly.
This rapid expansion creates a sonic shock wave — similar to a sonic boom — and that is what we hear as thunder.
- Statement 1 (meeting of cumulonimbus clouds)
- Statement 2 (lightning separating nimbus clouds)
- Statement 3 (upward movement of air)
All describe storm-related phenomena but none of them directly produces thunder.
The correct answer is (d) — none of the above.
Thunder is the sound created when lightning causes air to expand rapidly due to sudden extreme heat, producing a shock wave.
UPSC set a trap by listing storm-related phenomena that seem plausible but none actually produce thunder - only lightning does.
The question tests precise understanding of cause-and-effect in atmospheric physics, not just general storm knowledge.
Thunder and Lightning Formation
Geography thunder lightning thunderstorm
Thunder & Lightning: Formation Mechanism & UPSC Traps
Thunder is the sound produced by lightning, not by cloud movements
Lightning causes rapid air expansion due to extreme heat (30,000°C)
This expansion creates a sonic shock wave that we hear as thunder
Lightning and thunder occur simultaneously but we hear thunder later due to sound speed
What Produces Thunder
Thunder is the sound caused by lightning, not by cloud collisions or air movements. When lightning strikes, it heats the air to approximately 30,000°C — five times hotter than the sun's surface. This extreme heat causes the surrounding air to expand faster than the speed of sound, creating a sonic shock wave that we hear as thunder.
Thunder Formation Process
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Electrical discharge (lightning)**
Electric current flows through air channel`"]
s2["`**Extreme heating**
Air temperature reaches ~30,000°C instantly`"]
s3["`**Rapid air expansion**
Heated air expands faster than sound speed`"]
s4["`**Sonic shock wave**
Expansion creates pressure wave`"]
s5["`**Thunder sound**
We hear the shock wave as thunder`"]
s1 --> s2
s2 --> s3
s3 --> s4
s4 --> s5Thunder vs Lightning Facts
Lightning is the cause, thunder is the effect — they occur simultaneously
We see lightning before hearing thunder because light travels faster than sound
Distance to lightning = (Thunder delay in seconds) ÷ 3 in kilometers
Thunder can be heard up to 25 km away from lightning strike
Multiple lightning channels create the rumbling sound of prolonged thunder
Trap: Thunder is NOT caused by clouds meeting — this is about electrical discharge, not mechanical collision
Trap: Lightning doesn't 'separate' clouds — it's an electrical phenomenon within storm systems
Trap: Air movement creates storm conditions but doesn't directly produce the thunder sound
Key Error: Confusing storm formation processes with the specific thunder-generation mechanism
Cumulonimbus Clouds & Thunderstorms
Geography cumulonimbus clouds thunderstorm nimbus clouds
Cumulonimbus Clouds: Thunderstorm Formation & Characteristics
Cumulonimbus clouds are the main thunderstorm clouds with vertical development
They can extend from 500m to 18km in height with anvil-shaped tops
Form through convective processes with strong updrafts and downdrafts
Produce lightning, thunder, heavy rain, and sometimes hail and tornadoes
Thunderstorm Cloud Formation
Cumulonimbus clouds are massive vertical cloud formations that create thunderstorms. They develop through convective processes where warm, moist air rises rapidly, cools, and condenses. These clouds can tower from ground level to the tropopause (up to 18 km), creating the characteristic anvil shape at the top.
Cloud Types in Thunderstorms
Cloud Type | Height | Shape | Weather Produced |
|---|---|---|---|
Cumulus | Low to mid | Cotton-like, puffy | Fair weather, light showers |
Cumulonimbus | Surface to 18km | Towering anvil | Thunderstorms, lightning, heavy rain |
Nimbus | Low | Dark, shapeless | Steady rain or drizzle |
Nimbostratus | Low to mid | Grey layer | Continuous precipitation |
Thunderstorm Development Stages
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Developing stage**
Updrafts dominate, cumulus clouds grow vertically`"]
s2["`**Mature stage**
Cumulonimbus forms, lightning begins, heaviest precipitation`"]
s3["`**Dissipating stage**
Downdrafts dominate, storm weakens and moves away`"]
s1 --> s2
s2 --> s3Cumulonimbus Structure
Source: ScienceDirect.com — Cumulonimbus Clouds - an overview | ScienceDirect Topics · www.sciencedirect.com
Trap: Clouds don't 'meet' to produce thunder — individual cumulonimbus clouds generate their own electrical activity
Trap: Don't confuse nimbus (rain-bearing) with cumulonimbus (towering thunderstorm clouds)
Common Error: Thinking mechanical cloud collision creates thunder rather than electrical processes within clouds
Atmospheric Electricity & Charge Separation
Geography lightning upward movement air and water particles
Atmospheric Electricity: How Lightning Forms in Thunderstorms
Lightning forms through electrical charge separation within clouds
Ice crystals and water droplets colliding create positive and negative charges
Updrafts carry positive charges up, negative charges accumulate below
Electrical discharge occurs when potential difference becomes too great
Electrical Charge Buildup
Atmospheric electricity develops when ice crystals, water droplets, and hail collide within cumulonimbus clouds. These collisions transfer electrons, creating electrical charge separation. Strong updrafts carry lighter positively-charged particles upward while heavier negatively-charged particles remain in the lower cloud regions.
Lightning Formation Process
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Particle collision**
Ice crystals and water droplets collide in strong updrafts`"]
s2["`**Charge separation**
Positive charges move up, negative charges stay below`"]
s3["`**Electric field buildup**
Potential difference increases between cloud regions`"]
s4["`**Air breakdown**
Electric field overcomes air resistance`"]
s5["`**Lightning discharge**
Current flows through ionized air channel`"]
s1 --> s2
s2 --> s3
s3 --> s4
s4 --> s5Types of Lightning
Type | Path | Frequency | Characteristics |
|---|---|---|---|
Intra-cloud | Within same cloud | 75% of all lightning | Most common, not always visible |
Cloud-to-ground | Cloud to earth | 20% of all lightning | Most dangerous to humans |
Cloud-to-cloud | Between different clouds | 5% of all lightning | Occurs between storm systems |
Ground-to-cloud | Earth to cloud | Very rare | Upward lightning from tall objects |
Role of Updrafts
Updrafts are essential for charge separation but don't directly produce thunder
Vertical air speeds can reach 30 m/s in severe thunderstorms
Updrafts keep ice particles suspended, allowing more collisions and charge buildup
Downdrafts help complete the electrical circuit within the cloud system
Trap: Air movement creates conditions for lightning but doesn't produce the thunder sound itself
Key Distinction: Updrafts cause charge separation (lightning formation) not sound production (thunder)
Common Error: Confusing the prerequisite (air movement) with the direct cause (electrical discharge)