1. Wind Direction and Wind Speed
➥ The moving air is called wind.
Wind Direction: The direction from which the wind blows.
➥ Measured using a wind vane.
Wind Speed: The speed at which wind moves.
➥ Measured using an anemometer.
2. Air Pressure
➥ The force exerted by the air per unit area, measured in Pascals (Pa).
➥ Measured using Barometer
High and Low Pressure:
- High pressure: Cool and heavy air.
- Low pressure: Warm and light air.
3. Air Expands on Heating
➥ When air is heated, it becomes lighter and rises, creating a low-pressure area. This causes cooler air to flow in and replace it, generating wind.
4. Wind Currents and Their Reasons
➥ Wind currents are movements of air caused by differences in temperature and pressure.
Causes:
1. Uneven heating of the Earth's surface
2. rotation of the Earth
3. The presence of water bodies.
Explanation:
1. Uneven Heating of the Earth:
➥ The Sun heats the Earth unevenly. Regions near the equator receive more direct sunlight, making them warmer, while areas near the poles are cooler. This creates differences in temperature, leading to high-pressure and low-pressure zones, which in turn cause air to move, forming winds.
2. Uneven Heating of Land and Water:
Daytime: Land heats up faster than water. As the land gets warmer, the air above it rises, creating low pressure. Meanwhile, the air above the cooler water remains at higher pressure. The wind moves from the high-pressure area (over water) to the low-pressure area (over land). This is called the sea breeze.
Nighttime: Land cools down faster than water. The wind direction reverses, moving from land (high pressure) to water (low pressure). This is called the land breeze.
5. What is a Thunderstorm?
➥ A storm with thunder, lightning, heavy rain, and strong winds.
Formation: Caused by the rapid upward movement of warm air.
6. What to Do During a Thunderstorm?
➥ Stay indoors and away from windows.
➥ Avoid touching metal objects and electrical appliances.
➥ Do not take shelter under trees.
➥ If outside, crouch low to the ground in an open space.
7. How Does a Thunderstorm Become a Cyclone?
Heat and Moisture: Warm ocean water heats the air above it.
Low Pressure: Rising warm air creates a low-pressure area.
Rotation: The Coriolis effect causes the air to rotate, forming a cyclone.
8. Structure of a Cyclone
Eye: The calm center of the cyclone with low pressure.
Eye Wall: Surrounds the eye and has the strongest winds and heaviest rains.
Spiral Bands: Bands of clouds and rain extending outward.
9. Destructions Caused by Cyclones
➥ Strong winds cause damage to buildings, trees, and power lines.
➥ Heavy rains lead to floods and landslides.
➥ Storm surges flood coastal areas.
10. What is a Cloudburst?
➥ A sudden, heavy rainfall in a short period of time, often causing flash floods.
11. What is a Tornado?
➥ A rapidly rotating column of air that extends from a thunderstorm to the ground.
Appearance: Funnel-shaped with high-speed winds.
12. Disaster Preparedness
➥ Prepare an emergency kit with food, water, and first aid supplies.
➥ Secure loose objects around your home.
➥ Stay updated with weather alerts.
➥ Practice evacuation plans with your family.
13. Precautions During Thunderstorms, Cyclones, and Tornadoes
➥ Move to a safe shelter immediately.
➥ Stay away from windows, doors, and large open spaces.
➥ Follow official warnings and evacuation orders.
14. Advanced Disaster Warning Systems
Weather Satellites: Monitor weather conditions globally.
Doppler Radar: Tracks storms and predicts their intensity.
Mobile Alerts: Notify people of imminent dangers.
Community Warning Systems: Use sirens or loudspeakers to alert residents.
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