RBSE Solutions Class 8 Science Chapter 15 Natural Phenomena

Natural Phenomena Textbook Questions Solved

I. Multiple Choice Questions

Question 1.
1. With the increase in velocity of air, air pressure:
(a) Increases
(b) Decreases
(c) No change
(d) Become double
2. What will happen if air blows in between two balloons hanged on wooden stick separated by 10 cm distance:
(a) Balloons come near to each other
(b) Balloons goes away from each other
(c) Balloons burst
(d) No change
3. Centre of cyclone in a calm area is called:
(a) Center
(b) Eye
(c) Head
(d) Tail
Answer:
1. (b)
2. (a)
3. (b)
In simple words: When air moves faster, its pressure drops. Because of this, when air blows between two balloons, the lower pressure makes them move closer. The calm center of a cyclone is known as its eye.

🎯 Exam Tip: Remember that the relationship between air velocity and pressure is inverse. Faster air means lower pressure.

Question 2. Fill in the blanks
1. Tornado is dark coloured and funnel type................
2. The air flows from................pressure area to pressure area.
Answer:
1. Tornado is dark coloured and funnel type clouds.
2. The air flows from high pressure area to low pressure area.
In simple words: A tornado looks like a dark funnel cloud. Air always moves from places where there is a lot of pressure to places where there is less pressure.

🎯 Exam Tip: Understanding the basic characteristics of weather phenomena like tornadoes and the principles of air movement (high to low pressure) is key for these types of questions.

Natural Phenomena Short Answer Type Questions

Question 1. How does cyclones formed?
Answer: Water turns into vapor in the atmosphere by absorbing heat. When this vapor condenses back into water droplets, heat is released, making the surrounding air hot. This hot air then rises, which causes a drop in air pressure. To fill this space, faster air rushes in. This cycle repeats until a low-pressure area forms, around which layers of air begin to move in a spiral. This condition is called a cyclone, and its calm center is known as the eye of the cyclone.
In simple words: Cyclones form when warm, moist air rises, creating a low-pressure area. Cooler air rushes in, heats up, and rises, causing a repeating cycle of air spiraling inwards at high speeds around a calm center.

🎯 Exam Tip: When describing cyclone formation, ensure to mention the key steps: heat absorption, condensation, heat release, air rising, pressure drop, and spiraling air movement.

Question 2. What type of planning is needed to overcome the cyclone?
Answer:
Measures at social and government level:
1. The meteorological department should provide accurate forecasts and warnings about cyclones.
2. A rapid communication system is needed to warn fishermen, sailors, government agencies, and people in coastal areas quickly.
3. An efficient rescue operation system should be in place to move people to safe locations.
Activities done by people:
1. People should always pay attention to government warnings given on TV, radio, or in newspapers by the meteorological department.
2. Plans should be made to move important household items, farm animals, and vehicles to safer places.
3. It is important to avoid driving on roads that are flooded with water.
In simple words: To prepare for cyclones, the government needs to issue warnings, set up quick communication, and plan evacuations. People should listen to warnings, move their belongings and animals to safety, and avoid flooded roads.

🎯 Exam Tip: Categorize your answer into government/social measures and individual actions to provide a comprehensive response on cyclone preparedness.

Question 3. Describe an activity to explain air pressure.
Answer: Take a plastic bottle and fill it halfway with hot water. Then, quickly empty the water and immediately seal the bottle with its lid or cap. Now, pour cold water over the bottle. You will observe that the bottle crinkles or sticks inwards. This happens because some of the water vapor inside the bottle cools down and turns back into liquid water. This causes the air pressure inside the bottle to drop compared to the air pressure outside. The difference in air pressure makes the bottle contract. Many everyday activities like flying a kite, bursting balloons, raising a flag, dust blowing, and leaves rustling all demonstrate that air exerts pressure.
In simple words: If you put hot water in a plastic bottle, empty it, and seal it, then pour cold water on it, the bottle will shrink. This shows that when the air inside cools, its pressure drops, and the outside air pushes the bottle in, proving air has pressure.

🎯 Exam Tip: When explaining scientific concepts with an activity, clearly state the steps, what is observed, and the scientific reason behind the observation.

Question 4. What are the safety measures against the lightning thunder?
Answer:
Measures to protect from thunder lightning:
1. During a thunderstorm, do not stay in open areas; go inside a building.
2. It is best to remain indoors and not go outside the house.
3. Avoid activities like washing clothes or bathing during a thunderstorm.
4. Take shelter in a car or bus if you are outside.
5. Do not stand under tall or isolated trees.
6. Avoid lying down on open land.
In simple words: To stay safe from lightning, go inside a building or vehicle, avoid being outside, especially near tall trees or in open fields, and do not do water-related activities.

🎯 Exam Tip: Focus on finding immediate shelter in a safe place (indoors, vehicles) and avoiding high-risk areas (open fields, tall objects, water) when listing lightning safety measures.

Natural Phenomena Long Answer Type Questions

Question 1. What are the reasons of lightning thunder?
Answer: When the temperature rises, hot air moves upwards, carrying water vapor with it. As this air rises to colder areas, the water vapor condenses into water droplets. These droplets fall at high speed, and the friction caused by their interaction with the air and other water droplets creates an electrical discharge. This discharge generates a bright flash of light (lightning) and a loud sound (thunder). This natural phenomenon is called thunder lightning. Lightning is essentially a massive spark of electricity in the sky.
In simple words: Lightning and thunder happen when warm, wet air rises, and water droplets rub against each other as they fall. This rubbing builds up electricity, which causes a bright flash and a loud boom.

🎯 Exam Tip: Explain lightning formation as an electrical discharge resulting from friction between rising air and falling water droplets in clouds due to temperature differences.

Natural Phenomena Additional Questions Solved

I. Multiple Choice Questions

Question 1. Natural phenomena is
(a) Cyclones
(b) Thunderstorm
(c) Lightning
(d) All of the options
Answer: (d) All of the options
In simple words: Cyclones, thunderstorms, and lightning are all examples of things that happen naturally in nature.

🎯 Exam Tip: Natural phenomena are events that occur naturally in the environment without human intervention, such as weather events, geological processes, and biological cycles.

Question 2. Tornado affected area in INDIA is
(a) Western Ghat
(b) Eastern Ghat
(c) Northern Ghat
(d) Southern Ghat
Answer: (b) Eastern Ghat
In simple words: In India, the Eastern Ghats region is the area that is most often hit by tornadoes.

🎯 Exam Tip: Remember specific geographical areas associated with particular natural disasters, especially for regional questions.

Question 3. When warm air rises in upward direction, then
(a) Air pressure decreases
(b) Air pressure increases
(c) Air pressure remains unchanged
(d) None of the options
Answer: (a) Air pressure decreases
In simple words: When warm air moves up, the weight of the air above that area gets lighter, which makes the air pressure go down.

🎯 Exam Tip: Understand the inverse relationship between air temperature (and thus density) and air pressure: warmer, rising air leads to lower pressure.

Question 4. Lightning occurs due to:
(a) electricity discharge
(b) rain
Answer: (a) electricity discharge
In simple words: Lightning is caused by a sudden release of built-up electrical energy in the atmosphere, often during a thunderstorm.

🎯 Exam Tip: Define lightning as an electrical discharge, clarifying that rain is a related phenomenon but not the direct cause of the flash.

Question 5.
(a) destroys the building
(b) protects the building
(c) No effect
(d) none
Answer: (b) protects the building
In simple words: A lightning rod is designed to keep a building safe by redirecting lightning strikes safely into the ground.

🎯 Exam Tip: Although the question text is missing, infer from the options and answer that it refers to the function of a lightning rod, which is protection.

Question 6. The material used for lightning rods is:
(a) Copper
(b) Sand paper
(c) Plastic
(d) Bakelite
Answer: (a) Copper
In simple words: Lightning rods are typically made from copper because it is a very good conductor of electricity, allowing it to safely channel a lightning strike.

🎯 Exam Tip: Know that materials for lightning rods must be excellent electrical conductors, like copper, to safely ground the electrical charge.

Question 7. A thunderstorm is accompanied by:
(a) Tornado
(b) Cyclone
(c) Lightning
(d) All of the options
Answer: (d) All of the options
In simple words: Thunderstorms can happen with tornadoes, cyclones (though less common directly in a thunderstorm), and always include lightning.

🎯 Exam Tip: Thunderstorms are complex weather events that can lead to various related phenomena, including lightning, strong winds (potentially tornadic), and heavy rainfall, which can be part of broader cyclonic systems.

Question 8. Development and movement of cyclones are studied by the-
(a) Indian Postal Department
(b) Indian Forensic Department
(c) Indian Meteorological Department
(d) Central Investigation Department
Answer: (c) Indian Meteorological Department
In simple words: The Indian Meteorological Department is the government agency responsible for observing, forecasting, and studying weather patterns, including cyclones, in India.

🎯 Exam Tip: Recognize the roles of different government departments, especially those responsible for weather and disaster management.

Question 1. Define breeze.
Answer: Moving air is called breeze. It refers to a light, gentle wind.
In simple words: A breeze is just air that is moving gently.

🎯 Exam Tip: Keep definitions clear and concise, using simple language to explain basic concepts.

Question 2. Write the relation between velocity of air and air pressure?
Answer: When air velocity increases, air pressure reduces. This is a fundamental principle in fluid dynamics.
In simple words: As air moves faster, its pressure goes down.

🎯 Exam Tip: State the inverse relationship between air speed and pressure clearly, linking it to concepts like Bernoulli's principle without needing to name it.

Question 3. Which ghat of India is sensitive for cyclones?
Answer: The Eastern Ghats of India are particularly sensitive and vulnerable to cyclones. This is due to their geographical location along the Bay of Bengal.
In simple words: The Eastern Ghats in India are easily affected by cyclones.

🎯 Exam Tip: Identify specific geographical features or regions that are prone to certain natural disasters.

Question 4. What is tornado called in USA and Japan?
Answer: A tornado is called a hurricane in America (USA) and a typhoon in Japan. These are all names for severe rotating storms.
In simple words: In America, a tornado is called a hurricane, and in Japan, it's called a typhoon.

🎯 Exam Tip: Note the different regional names for similar weather phenomena to show a broader understanding.

Question 5. Give the main reason of air current flow.
Answer: The main reason for air current flow is the non-uniform heating pattern at the equatorial and polar regions. This creates temperature and pressure differences that drive air movement.
In simple words: Air moves because different parts of the Earth, like near the equator and the poles, get heated unevenly.

🎯 Exam Tip: Emphasize uneven heating as the primary driver of global air circulation and wind currents.

Question 6. What is tornado?
Answer: A tornado is a dark-colored, funnel-shaped cloud that appears to come down from the sky towards the Earth. It is a violently rotating column of air.
In simple words: A tornado is a dark, spinning cloud shaped like a funnel that reaches from the sky to the ground.

🎯 Exam Tip: Describe a tornado by its key visual characteristics: dark, funnel-shaped, and connecting sky to ground.

Question 7. How does monsoon winds caused?
Answer: Monsoon winds are caused by the uneven heating of land and sea. During summer, land heats up faster and more intensely than the sea, creating low pressure over land, which draws in moisture-laden winds from the sea.
In simple words: Monsoon winds happen because the land and the sea heat up differently. This makes winds blow from the sea to the land, bringing rain.

🎯 Exam Tip: Link monsoon formation to the differential heating of land and sea, explaining how it creates pressure gradients that drive wind direction.

Question 9. What is eye of cyclone?
Answer: The eye of a cyclone refers to the calm conditions that prevail at the very center of the cyclone. It is typically a clear, cloud-free area.
In simple words: The "eye" of a cyclone is the quiet, peaceful area right in the middle of the storm.

🎯 Exam Tip: Define the eye of a cyclone by its key characteristic: an area of calm weather at the storm's center, contrasting with the violent winds around it.

Question 10. What does cyclone consist of?
Answer: A cyclone consists of a low-pressure area at its center, surrounded by areas of higher pressure. High-speed winds then circulate violently around this central low-pressure zone.
In simple words: A cyclone is made of a low-pressure spot in the middle, with high-pressure air all around it, causing very fast winds to spin violently.

🎯 Exam Tip: Describe a cyclone by its core components: a low-pressure center, high-pressure surroundings, and high-speed winds circulating around it.

Natural Phenomena Short Answer Type Questions

Question 1. Make a list of four incidences which are related to air pressure.
Answer:
1. Kites flying in the air.
2. Flag waving in the wind.
3. Flying of leaves and soil particles due to wind.
4. Overfilled balloons bursting.
In simple words: Air pressure helps kites fly, flags wave, leaves move, and makes balloons pop if they are too full.

🎯 Exam Tip: Provide clear and distinct examples that directly illustrate the effects of air pressure in everyday observations.

Question 2. What is lightning conductor ?How does it protect building from lightning?
Answer: A lightning conductor is a safety device used to protect buildings from the damaging effects of lightning. It is a metallic rod, taller than the building, installed into the walls during construction. One end of the rod extends into the air, and the other end is buried deep in the ground. The conductor provides an easy and direct path for the electricity from a lightning strike to safely transfer into the ground, preventing damage to the building.
In simple words: A lightning conductor is a tall metal rod on a building that guides lightning safely into the ground. This stops the lightning from damaging the building.

🎯 Exam Tip: When explaining a lightning conductor, describe its physical structure (tall metallic rod, grounded) and its function (provides a safe path for electrical discharge).

Question 3. Why is it difficult to insert paper ball in bottle by blow of air?
Answer: When we blow air towards the mouth of a bottle, the velocity of the air increases at that point. According to Bernoulli's principle, an increase in air velocity causes a decrease in air pressure. This creates a lower pressure zone at the bottle's mouth compared to the higher pressure inside the bottle. As a result, the higher pressure inside pushes the paper ball back out, making it difficult to insert it.
In simple words: It's hard to blow a paper ball into a bottle because when you blow, the air at the bottle's opening moves faster. This faster air has lower pressure, so the higher pressure inside the bottle pushes the paper ball back out.

🎯 Exam Tip: Explain this phenomenon by linking increased air velocity to decreased air pressure, creating a pressure difference that pushes the object away.

Question 5. Explain the safety measures at government or social level?
Answer:
Safety measures at government or social level:
1. The meteorological department issues forecasts and warnings about cyclones to inform the public.
2. Rapid communication facilities are crucial to quickly provide information to fishermen, boat operators, government agencies, coastal communities, and the general public.
3. Efficient transportation methods are needed to relocate people to safe places before a cyclone hits.
In simple words: Governments and society need to forecast cyclones, quickly tell people what to do, and help move everyone to safe places to keep them out of harm's way.

🎯 Exam Tip: When discussing safety measures, differentiate between the actions taken by authorities (forecasting, communication, evacuation) and those taken by individuals.

Question 6. What work should be done by the public for safety?
Answer:
1. People should always pay attention to the warnings issued by the meteorological department, broadcast on radio, television, or published in newspapers.
2. It is important to make arrangements to move essential household items, domestic animals, and vehicles to a safe zone.
3. Avoid driving vehicles on flooded roads, as this can be extremely dangerous.
4. Keep the telephone numbers of emergency services, such as the police, fire brigade, and hospitals, readily available.
In simple words: For safety, people should listen to warnings, move their things and animals to safe spots, stay off flooded roads, and have emergency numbers ready.

🎯 Exam Tip: Focus on actionable advice for individuals, including staying informed, preparing property, avoiding danger, and knowing how to contact help.

Cyclones are huge, very powerful storms. They can be hundreds of kilometers wide. They form only in warm, wet conditions, usually over the sea in tropical areas near the equator. The sequence of events that lead to the formation of cyclone is as follows:

1. When water from the sea evaporates, it takes up heat from the atmosphere to change into water vapour.

2. Air over the sea gets heated by the sun. As the warm air rises, it is located with moisture from the sea.

3. As this air gets heated, it becomes lighter and rises up further, causing a low pressure region to develop. More air rushes in towards the center of the low pressure region.

4. This process continues and results in a very low pressure region in the center with very high speed winds revolving around it. The swirling winds rotate faster and faster, forming a huge circle which can be upto 200 km across.

Question 2. Explain the wind currents due to uneven heating of land and water.
Answer: Land and sea winds occur because land heats up more quickly during the day but also cools down faster at night compared to water. In summer, the land over India becomes warmer than the surrounding sea. This difference causes winds to blow from the cooler sea towards the warmer land. These winds come from the southwest and carry moisture from the Indian Ocean, bringing rain to most parts of India. In winter, the direction of the winds reverses, flowing from land to sea. These winds carry less moisture, resulting in minimal rainfall.
In simple words: Wind currents happen because land and water heat up and cool down at different speeds. During summer, warm land pulls cool, moist air from the sea, causing rain. In winter, the flow reverses.

🎯 Exam Tip: When explaining wind currents, highlight the concept of differential heating between land and water, and how it leads to pressure differences and wind movement.

Question 3. Mention the ill effects of cyclone that occurred in Odisha in 2013.
Answer: On October 12, 2013, at 9:00 pm, rotating winds moving at 220 km/hr collided with the Odisha coast, bringing heavy rain. High waves surged into the sea, causing seawater to enter coastal areas. These strong winds and water severely damaged houses and flooded vast areas of agricultural land, destroying crops and uprooting electric poles. Widespread darkness resulted, and many people lost their lives. This devastating natural phenomenon is known as a Cyclone. In the American continent, it is called a 'Hurricane', and in Japan, a 'Typhoon'.
In simple words: The 2013 Odisha cyclone caused widespread damage, including destruction of houses, crops, and infrastructure due to high-speed winds, heavy rain, and coastal flooding, leading to loss of life.

🎯 Exam Tip: Provide specific details like date, speed, and types of damage (houses, crops, infrastructure, human life) when describing the effects of a particular disaster.

Question 4. Explain how lightning occurs in Thunderstorm.
Answer: Lightning is an electrical discharge that takes place within the clouds during a thunderstorm. A thundercloud contains numerous frozen water droplets and small ice pieces. As wind blows, these frozen particles collide, becoming electrically charged through friction. This process fills the entire cloud with electrical charges. Typically, positive charges accumulate at the top of the cloud, while negative charges gather near the lower edges.
A positive charge area also develops on the ground beneath the cloud due to friction with wind and rain, accumulating near the ground and on treetops. The strong attraction between these opposite charges can cause electrons to jump the air gap between objects. Once a few electrons cross, they rapidly heat the air, causing more electrons to follow. This rapid heating makes the air glow brightly for a short period, creating a spark that we see as lightning.
In simple words: Lightning happens in thunderstorms when ice and water particles rub together in clouds, building up electric charges. These charges create a huge spark that lights up the sky as they jump between different charged areas in the cloud or to the ground.

🎯 Exam Tip: Detail the process of charge separation (positive at top, negative at bottom of cloud, positive on ground) and the rapid electrical discharge that produces light and sound.