Air Class 7 Worksheet Geography Chapter 4

Q.1. What is the instrument that measures the amount of rainfall?

Rain Gauge A rain gauge is an instrument used to measure the amount of rainfall. It helps in:

• Collecting rainwater in a graduated container.
• Providing accurate measurements of precipitation.
• Assisting in weather forecasting and agricultural planning.

This tool is essential for understanding local weather patterns and managing water resources effectively.

Q.2. What do you understand by climate of a place?

The climate of a place refers to the average weather conditions over a long period. Key points include:

• It encompasses patterns of temperature, humidity, and precipitation.
• Climate is typically assessed over decades or longer.
• It differs from weather, which describes short-term atmospheric conditions.

Understanding climate helps us predict long-term trends and prepare for seasonal changes.

Q.3. Why amount of insolation decreases from equator towards poles?

The amount of insolation decreases from the equator to the poles due to the angle at which sunlight strikes the Earth:

• At the equator, sun rays hit the surface almost vertically, covering a smaller area.
• At the poles, sun rays strike at a slanting angle, spreading over a larger area.

As a result, the total energy received per unit area is less at the poles compared to the equator.

Q.4. How does nature maintain a balance of oxygen and carbon dioxide in the atmosphere? What is the result of this balance get disturbed?

Oxygen is the second most abundant gas in the atmosphere. Humans and animals breathe in oxygen, while green plants produce it through photosynthesis. This process helps maintain a constant level of oxygen in the air. However, cutting down trees can disrupt this balance. Carbon dioxide is another crucial gas. Plants use carbon dioxide to create food and release oxygen. The amount of carbon dioxide produced by humans and animals is roughly equal to what plants consume, creating a natural balance. Unfortunately, this balance is disturbed by the burning of fossil fuels, such as coal and oil, which release billions of tonnes of carbon dioxide into the atmosphere each year. This increase in carbon dioxide levels:

• Affects the Earth's weather and climate.
• Contributes to the greenhouse effect, trapping heat and leading to global warming.
• Causes melting ice caps, resulting in rising sea levels and potential flooding in coastal areas.
• May lead to drastic climate changes, threatening the survival of various plant and animal species.

Q.5. What is the standard unit of measurement for temperature?

The standard unit for measuring temperature is the degree Celsius. This scale was developed by Anders Celsius. Key points include:

• Water freezes at 0°C.
• Water boils at 100°C.

Q.6. How are winds named?

A wind is named based on the direction it comes from. For example:

• The wind blowing from the west is called westerly.
• The wind blowing from the north is called northerly.
• The wind blowing from the east is called easterly.
• The wind blowing from the south is called southerly.

This naming convention helps in understanding weather patterns and forecasting.

Q.7. Why do astronauts wear space suits on the moon?

Astronauts wear special protective space suits on the moon for several important reasons:

• There is no air on the moon, which means there is no air pressure.
• The suits are filled with air to provide necessary counter pressure.
• Without these suits, the pressure from the body could cause blood vessels to burst, leading to severe bleeding.

Q.8. Write a short note on the distribution of air pressure in atmosphere?

Air pressure is the force exerted by the weight of air on the Earth's surface. Its distribution varies with altitude and temperature:

• Highest pressure is found at sea level, decreasing rapidly with height.
• In warmer areas, air heats up and rises, creating a low-pressure zone.
• Low pressure often leads to cloudy skies and wet weather.
• Conversely, in cooler regions, heavy air sinks, resulting in a high-pressure area.
• High pressure is typically associated with clear and sunny conditions.

Air moves from high-pressure areas to low-pressure areas, which is what we experience as winds.

Q.9. Which gas protects us from harmful sun rays?

Ozone is the gas that protects us from the harmful effects of the sun's rays.

Q.10. What are the three main types of winds?

Winds can be classified into three main types:

• Permanent winds: These winds blow consistently throughout the year in a specific direction. Examples include trade winds, westerlies, and easterlies.
• Seasonal winds: These winds change direction with the seasons. A well-known example is the monsoon winds in India.
• Local winds: These winds occur in a specific area and only during certain times of the day or year. Examples include land and sea breezes, as well as the hot, dry wind known as "loo" in northern India.

Q.11. Why is the atmosphere essential for life?

All living beings on Earth rely on the atmosphere for survival. It provides:

• The air we breathe.
• Protection from harmful sun rays.

Without this protective layer, we would face extreme temperatures:

• During the day, we would be scorched by the sun.
• At night, we would freeze.

Thus, the atmosphere plays a crucial role in making Earth's temperature suitable for life.

Q.12. What is the composition of the atmosphere?

The air we breathe is a mixture of various gases. The main components of the atmosphere are:

• Nitrogen: 78%
• Oxygen: 21%
• Argon: 0.93%
• Carbon dioxide: 0.03%
• Helium, ozone, and hydrogen: found in smaller amounts

Additionally, tiny dust particles are present in the air. This mixture is essential for life on Earth.

Q.13. What is the role of the ozone layer?

The ozone layer plays a crucial role in protecting life on Earth. It does this by:

• Absorbing the majority of the sun's harmful ultraviolet (UV) radiation.
• Preventing skin cancer and other health issues caused by excessive UV exposure.
• Protecting ecosystems, particularly marine life, from UV damage.

In summary, the ozone layer is essential for maintaining a safe environment for all living beings.

Q.14. What is global warming?

Global warming occurs when the level of carbon dioxide in the atmosphere rises due to emissions from factories and vehicles. This increase in carbon dioxide leads to more heat being trapped, which raises the Earth's temperature.

• Higher levels of carbon dioxide create a greenhouse effect.
• This effect causes the planet to warm up.
• As a result, ice in polar regions melts, leading to rising sea levels.
• Rising sea levels can cause flooding in coastal areas.
• Long-term effects may include drastic climate changes and the extinction of some species.

Q.15. How do bacteria help plants use nitrogen?

Bacteria play a crucial role in helping plants utilise nitrogen. Here’s how:

• Plants require nitrogen for growth but cannot absorb it directly from the air.
• Soil-dwelling bacteria convert atmospheric nitrogen into forms that plants can use.
• This process enriches the soil, making it more fertile.