Chapter 6 – Pressure, Winds, Storms, and Cyclones (Class 8 Science | NEP 2025 Pattern)

🧭 Chapter Overview

Air is not just empty space — it’s a powerful force that can move oceans, shake trees, and even cause massive cyclones.
This chapter, “Pressure, Winds, Storms, and Cyclones,” explores how air pressure and temperature differences cause wind, how winds lead to storms, and how nature’s most powerful systems — cyclones — form and behave.

By the end of this chapter, you’ll understand the science behind weather, how to predict wind directions, and how humans can prepare for and survive cyclones using knowledge and technology.

---

🎯 Learning Objectives (NEP 2025 Competency Table)

Competency	Learning Outcome	NEP Skill
Conceptual Understanding	Explain air pressure and factors affecting it	Analytical Thinking
Inquiry-Based Learning	Demonstrate pressure experiments	Scientific Inquiry
Application	Relate pressure differences to wind formation	Real-Life Connection
Environmental Awareness	Describe cyclone causes & safety	Sustainability Awareness
Values Integration	Learn human responsibility in disasters	Citizenship & Ethics

---

🌬️ 6.1 What Is Air Pressure?

Air has weight — it presses on everything around us.
The force exerted by air per unit area is called air pressure. Pressure=ForceArea\text{Pressure} = \frac{\text{Force}}{\text{Area}}Pressure=AreaForce​

🌡️ Key Points:

• Air exerts pressure in all directions.
• Pressure decreases with height (less air above you).
• Temperature affects pressure — warm air is lighter, cool air is heavier.

---

🧪 Activity: Pressure in Action

Aim: To show that air exerts pressure.
Materials: Glass, water, and cardboard.
Procedure:

1. Fill glass ¾ with water.
2. Cover with cardboard and invert.
3. The water doesn’t fall!

Explanation:
Air pressure acting upward balances the weight of water.

💡 Invisible air can hold up visible water — that’s the power of pressure!

---

🌪️ 6.2 How Are Winds Formed?

Winds are caused by differences in air pressure.
Air moves from a high-pressure area to a low-pressure area.

☀️ Heat and Wind

When the Sun heats Earth’s surface unevenly:

• Warm air rises (low pressure).
• Cool air sinks (high pressure).
• Air movement between these zones creates wind.

---

🌊 Land Breeze and Sea Breeze

Type	Time	Direction	Explanation
Sea Breeze	Day	Sea → Land	Land heats faster; warm air rises over land; cool sea air flows in.
Land Breeze	Night	Land → Sea	Land cools faster; warm air rises over sea; cool land air replaces it.

🌅 That gentle beach wind you feel? It’s nature balancing temperatures.

---

🧭 Global Wind Patterns

Earth’s rotation and sunlight create permanent wind systems:

• Trade Winds – Blow from east to west near equator.
• Westerlies – Blow from west to east in temperate regions.
• Polar Winds – Blow from poles toward lower latitudes.

🌍 These winds influence weather, rainfall, and ocean currents.

---

🌫️ 6.3 Air Pressure and Weather

Air pressure helps meteorologists predict weather.

Air Pressure	Air Movement	Weather
Low Pressure	Warm air rising	Cloudy, stormy
High Pressure	Cool air sinking	Clear, dry

🌦️ A sudden drop in air pressure often means a storm is coming.

---

⚡ 6.4 What Are Storms?

A storm is a violent disturbance in the atmosphere caused by rapid air movement due to pressure differences.

🌩️ Types of Storms

Type	Description	Example
Thunderstorm	Heavy rain + thunder + lightning	Summer storms
Dust Storm	Strong winds carrying sand	Deserts
Snowstorm	Heavy snow + wind	Mountains
Cyclone / Hurricane / Typhoon	Powerful rotating storm over oceans	Coastal regions

---

🌈 Thunderstorms and Lightning

Lightning is caused by electric discharge between clouds or between cloud and ground.

⚠️ Safety Tips During Lightning:

• Don’t stand under trees.
• Stay indoors and unplug electronics.
• Avoid open fields and water.
• Sit on the floor (not metal objects).

⚡ Lightning travels faster than sound — that’s why you see the flash before hearing thunder.

---

🌊 6.5 Cyclones – Nature’s Giant Whirlwinds

A cyclone is a huge rotating storm system that forms over warm ocean water.

🌪️ Conditions for Cyclone Formation

1. Warm ocean water (≥ 27°C)
2. High humidity
3. Low air pressure
4. Earth’s rotation (Coriolis effect)

---

🌀 Structure of a Cyclone

Part	Description
Eye	Calm center of the cyclone
Eye Wall	Surrounding area with strongest winds
Rain Bands	Spiraling clouds causing rain & floods

---

🌍 Cyclone Naming & Regions

Region	Local Name	Example
Indian Ocean	Cyclone	Cyclone Amphan
Atlantic Ocean	Hurricane	Hurricane Katrina
Pacific Ocean	Typhoon	Typhoon Haiyan

🧠 All three are the same weather phenomenon — just different regional names!

---

🚨 Effects of Cyclones

🌧️ Heavy Rainfall → Floods
💨 Strong Winds → Damage to houses, crops, and power lines
🌊 Storm Surges → Coastal flooding

---

🛡️ Precautions During Cyclones

Before	During	After
Listen to weather forecasts	Stay indoors	Avoid flooded areas
Store food & water	Disconnect power	Drink clean water
Pack emergency kit	Stay away from windows	Help neighbors

📻 India’s IMD (Indian Meteorological Department) monitors cyclones and issues early warnings through satellites and radar.

---

🌎 6.6 India’s Major Cyclones

Cyclone	Year	Impacted States	Impact
Odisha Super Cyclone	1999	Odisha	10,000+ lives lost
Cyclone Amphan	2020	Bengal, Odisha	Severe floods
Cyclone Yaas	2021	Bengal, Jharkhand	Widespread damage
Cyclone Tauktae	2021	Gujarat, Maharashtra	Coastal destruction

🇮🇳 Disaster preparedness has reduced cyclone-related loss by 70% since 2000.

---

🌱 6.7 Disaster Preparedness and Mitigation

To prevent loss during storms and cyclones, India follows a 3-step safety plan:

1️⃣ Prediction & Warning Systems:

• Satellites and Doppler Radars track cyclone movement.
• Alerts shared through IMD and NDMA.

2️⃣ Preparedness:

• Evacuate coastal areas early.
• Build cyclone shelters.
• Educate communities.

3️⃣ Response & Recovery:

• Rescue operations by NDRF.
• Relief camps, medical aid, rebuilding support.

---

🧠 HOTS (Higher Order Thinking Skills)

1. Why do cyclones form only over warm seas and not land?
2. How can air pressure predict a storm?
3. Why is a tornado smaller but more intense than a cyclone?
4. How does deforestation increase cyclone impact?
5. How do satellites help in reducing cyclone damage?

---

⚙️ NEP COMPETENCY FRAMEWORK

Domain	NEP Skill	Activity
Conceptual	Explain pressure & cyclone formation	Diagram + explanation
Analytical	Analyze weather data	Graph reading
Practical	Demonstrate pressure activity	Glass-card experiment
Creative	Design awareness poster	“Stay Safe During Cyclone” campaign
Ethical	Promote disaster management	School mock drill

---

💡 Memory Booster Box

🔹 Air exerts pressure in all directions
🔹 Wind moves from high to low pressure
🔹 Warm air = light; cool air = heavy
🔹 Cyclones form over warm oceans
🔹 IMD tracks and names cyclones
🔹 Safety = Awareness + Preparedness

---

⚠️ Exam Alert Box

📍 Define: Air pressure, Cyclone, Frictional force of air
📍 Differentiate: Land breeze vs Sea breeze
📍 Explain: Conditions for cyclone formation
📍 Diagram: Structure of a cyclone
📍 Value Question: Role of humans in disaster management

---

📘 Quick Recap

✅ Air pressure changes cause winds
✅ Uneven heating → Pressure differences → Wind movement
✅ Low pressure = storms and rainfall
✅ Cyclones form over warm oceans
✅ Preparedness reduces disaster loss

---

🔗 INTERNAL & EXTERNAL LINKS

Internal Links (A2ZLY):

• Chapter 5 – Exploring Forces Notes 2025
• Class 8 Science All Chapters Smart Notes 2025
• NEP 2025 Smart Learning Hub | A2ZLY

External Links:

• NCERT Official Site
• IMD Cyclone Tracking Portal
• NDMA Disaster Management Portal