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Heat and its Measurement - Sea Breeze and Land Breeze

Grade 7CBSE

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

🔑Concepts

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Convection in Air: Sea breeze and land breeze are natural examples of convection currents occurring in coastal areas.

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Differential Heating: Land heats up faster than water during the day and cools down faster than water at night. This difference in the rate of heating and cooling drives the movement of air.

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Sea Breeze: During the day, the land gets heated by the sun more quickly than the sea. The air above the land becomes warmer, its density ρ\rho decreases, and it rises. The cooler air from the sea rushes in towards the land to take its place.

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Land Breeze: At night, the land loses heat faster than the sea. The water remains warm for a longer duration. Consequently, the air above the sea is warmer and rises. The cool air from the land moves towards the sea to fill the gap.

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Temperature and Pressure: Warm air creates a region of low pressure as it expands and rises, while cool air represents a region of high pressure. Air always moves from high-pressure areas to low-pressure areas.

📐Formulae

Q=mcΔTQ = mc\Delta T

ρ=mV\rho = \frac{m}{V}

Tland>Tsea (Daytime condition for Sea Breeze)T_{land} > T_{sea} \text{ (Daytime condition for Sea Breeze)}

Tsea>Tland (Nighttime condition for Land Breeze)T_{sea} > T_{land} \text{ (Nighttime condition for Land Breeze)}

💡Examples

Problem 1:

In a coastal region, a person notices that the windows of houses usually face the sea. Why is this design preferred for the daytime?

Solution:

This is done to receive the Sea Breeze.

Explanation:

During the day, the land becomes hotter than the sea. The hot air over the land rises, and the cool air from the sea (Tsea<TlandT_{sea} < T_{land}) blows towards the land. Windows facing the sea allow this cool sea breeze to enter the house, providing a natural cooling effect.

Problem 2:

Compare the temperature of air over the land (TLT_L) and sea (TST_S) at 10:00 PM and predict the direction of wind flow.

Solution:

At 10:00 PM, TS>TLT_S > T_L. The wind flows from the land to the sea.

Explanation:

At night, the land cools down faster than the water due to its lower specific heat capacity. Therefore, the air over the sea is warmer (TST_S) and rises. The cooler, denser air from the land (TLT_L) moves towards the sea, creating a Land Breeze.