Composition and Structure of Atmosphere


1. Multiple choice questions.

(i) Which one of the following gases constitutes the major portion of the atmosphere?

(a) Oxygen (c) Argon

(b) Nitrogen (d) Carbon dioxide

Answer: (b) Nitrogen.



(ii) Atmospheric layer important for human beings is:

(a) Stratosphere (c) Troposphere

(b) Mesosphere (d) Ionosphere

Answer: (c) Troposphere


(iii) Sea salt, pollen, ash, smoke soot, fine soil — these are associated with:

(a) Gases (c) Water vapour

(b) Dust particles (d) Meteors

Answer: (b) Dust particles.


(iv) Oxygen gas is in negligible quantity at the height of atmosphere:

(a) 90 km (c) 100 km

(b) 120 km (d) 150 km

Answer: (b) 120 km.


(v) Which one of the following gases is transparent to incoming solar radiation and opaque to outgoing terrestrial radiation?

(a) Oxygen (c) Helium

(b) Nitrogen (d) Carbon dioxide

Answer: (d) Carbon dioxide.


2. Answer the following questions in about 30 words.

(i) What do you understand by atmosphere?

Answer: Earth's invisible blanket! A mix of gases like oxygen and nitrogen that shields us from harmful rays, keeps us warm, and fuels weather wonders. It's the air we breathe and the playground for clouds and storms. Think of it as a dynamic, protective shell wrapping our planet.


(ii) What are the elements of weather and climate?

Answer: Weather's daily tantrums come down to five key elements:

*Temperature: How hot or cold it feels.

*Precipitation: Rain, snow, hail, or sunshine!

*Wind: From gentle breezes to fierce gusts.

*Humidity: How much moisture hangs in the air.

*Cloudiness: Fluffy blankets or clear blue skies.

    Climate, though, tells a longer story, reflecting patterns of these elements over years, shaping ecosystems and landscapes. It's like weather's patient cousin, remembering all the ups and downs!


(iii) Describe the composition of atmosphere.

Answer: Air has layers! Mostly, it's nitrogen (like 78%) and oxygen (around 21%). Then there's argon (just over 0.9%) and trace amounts of other gases like carbon dioxide, important for keeping us warm but too much causes trouble. Think of it as a mix, essential for life and always on the move!


(iv) Why is troposphere the most important of all the layers of the atmosphere?

Answer: The Troposphere reigns supreme because it's where life thrives! It holds:

*Our breath: 80% of the air we breathe (mostly oxygen!)

*Weather wonderland: Clouds, rain, wind, all play here, shaping our daily lives.

*Heat haven: Traps warmth from the sun, keeping us cozy (with a little help from greenhouse gases).

    No other layer offers such a vital cocktail for life and everyday drama. Troposphere - Earth's living room, weather stage, and breath of life!


3. Answer the following questions in about 150 words.

(i) Describe the composition of the atmosphere.

Answer: Imagine Earth's air as a layered cocktail, and here's the recipe:

Main Ingredients:

*Nitrogen (78.08%): The silent majority, forming the bulk of the atmosphere and diluting reactive gases like oxygen.

*Oxygen (20.95%): Essential for life, fueling respiration and combustion.

Flavorful Spices:

*Argon (0.93%): Inert and abundant, adding stability to the mix.

*Carbon dioxide (0.04%): A trace gas with a big impact, trapping heat and contributing to the greenhouse effect.

Aromatic Hints:

*Water vapor: Variable amounts, creating clouds and influencing weather patterns.

*Trace gases: Neon, helium, methane, and others, playing specific roles in atmospheric chemistry and climate.

Layers Like Liqueurs:

*Troposphere (0-10 km): Closest to Earth, with most air mass and weather phenomena.

*Stratosphere (10-50 km): Contains the ozone layer, shielding us from harmful solar radiation.

*Mesosphere (50-80 km): Cold and rarefied, with little impact on weather or life.

*Thermosphere (80-500 km): Thin air, heated by the sun, causing auroras and influencing satellites.

*Exosphere (500 km+): The final frontier, where air molecules escape into space.

    So, remember, Earth's atmosphere is a dynamic mix of gases, playing a crucial role in life, weather, and protecting our planet from harm. It's a unique cocktail, constantly evolving and shaping our world, one breath at a time.


(ii) Draw a suitable diagram for the structure of the atmosphere and label it and describe it.

Answer: Unfortunately, I can't directly generate images within chat yet. However, I can describe a simple diagram of the atmosphere's structure for you to visualize:

Imagine a vertical cross-section of Earth with concentric layers around it, like an onion.

*Troposphere (Closest to Earth, 0-10 km): Thickest layer, contains 80% of the atmosphere's mass, marked by weather activity like clouds, rain, and storms. Label it "Troposphere" and show clouds and lightning symbols.

*Stratosphere (10-50 km): Thinner layer, contains the ozone layer that protects us from UV radiation. Label it "Stratosphere" and add a shield symbol for the ozone layer.

*Mesosphere (50-80 km): Cold and rarefied layer, with meteor trails sometimes visible. Label it "Mesosphere" and add a shooting star symbol.

*Thermosphere (80-500 km): Very thin air, heated by the sun, causing auroras and influencing satellites. Label it "Thermosphere" and add an aurora borealis symbol.

*Exosphere (500 km+): The outermost layer, where air molecules escape into space. Label it "Exosphere" and show fading air molecules.

    Remember, this is a simplified version. The actual boundaries and temperatures of the layers can vary.



Answer Type By: Himashree Bora.