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Air, Water, and Weather - Understanding Weather and Seasons

Grade 4CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Weather is the condition of the atmosphere of a place at a particular time, influenced by temperature, wind, and moisture.

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The atmosphere is composed of gases like Nitrogen (N2≈78%N_2 \approx 78\%), Oxygen (O2≈21%O_2 \approx 21\%), and trace amounts of Carbon Dioxide (CO2CO_2) and water vapor (H2OH_2O).

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The Earth's axis is tilted at an angle of 23.5∘23.5^\circ. This tilt, combined with the Earth's revolution around the Sun, causes different seasons: Summer, Winter, Monsoon, Autumn, and Spring.

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Evaporation is the process where liquid H2OH_2O changes into water vapor due to heat. Factors like high temperature, wind speed, and large surface area increase the rate of evaporation.

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Condensation is the process where water vapor cools down to form liquid H2OH_2O droplets, leading to the formation of clouds, dew, or fog.

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Sea Breeze occurs during the day when land heats up faster than water; the warm air above land rises and cool air from the sea moves in to take its place.

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Land Breeze occurs at night when land cools down faster than the sea; the warm air above the sea rises and cool air from the land moves toward the sea.

📐Formulae

Rate of Evaporation∝Temperature\text{Rate of Evaporation} \propto \text{Temperature}

Composition of Air=78%N2+21%O2+1%Other Gases\text{Composition of Air} = 78\% N_2 + 21\% O_2 + 1\% \text{Other Gases}

Earth’s Tilt=23.5∘\text{Earth's Tilt} = 23.5^\circ

💡Examples

Problem 1:

During a hot summer day, why does a puddle of water (H2OH_2O) disappear faster than on a cool day?

Solution:

The puddle disappears faster because of an increased rate of evaporation.

Explanation:

Higher temperatures provide more heat energy to the H2OH_2O molecules, allowing them to escape into the air as water vapor more quickly. Since Evaporation∝Temperature\text{Evaporation} \propto \text{Temperature}, the process accelerates on hot days.

Problem 2:

Identify the process when you see water droplets on the outer surface of a cold glass of water.

Solution:

The process is called Condensation.

Explanation:

The water vapor (H2OH_2O in gas form) present in the surrounding air comes into contact with the cold surface of the glass. It loses heat energy and changes back into liquid H2OH_2O droplets.

Problem 3:

Explain why seasons change on Earth.

Solution:

Seasons change due to the Earth's tilt of 23.5∘23.5^\circ and its revolution around the Sun.

Explanation:

As the Earth revolves, different parts of the Earth are tilted towards or away from the Sun. The hemisphere tilted towards the Sun receives direct sunlight and experiences Summer, while the hemisphere tilted away experiences Winter.