NCERT Class 11 Geography — Chapter 2: Movements of Ocean Water

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Near the equator, the ocean water level is approximately 8 cm higher than in the middle latitudes. What is the primary reason for this?

Official previous-year question

Verified 1 Aug 2026.

Options

AHeating by solar energy causing water expansion.
BExcessive rainfall at the equator.
CStrong trade winds piling up water.
DLow gravitational pull at the equator.

Did you get this right?

Solution

The correct option is Heating by solar energy causing water expansion..

Explanation

The variation in sea level across different latitudes is primarily influenced by the physical properties of seawater, specifically density changes driven by temperature.

Detailed Analysis:

Thermal Expansion: The equatorial region receives the most direct and intense solar insolation throughout the year. This results in significantly higher sea surface temperatures compared to the middle and high latitudes.
Volume Increase: As water warms, its density decreases, and it undergoes thermal expansion. This means that a column of warm water occupies a greater volume than an equivalent mass of cold water.
Sea Level Rise: Due to this expansion, the ocean surface at the equator stands approximately 8 cm higher than in the middle latitudes. This slight gradient contributes to the flow of ocean currents as water tends to flow down the slope.

Key Takeaway: Intense solar heating at the equator causes thermal expansion of seawater, resulting in a slightly higher sea level compared to cooler latitudes.

Your note

More from Chapter 2: Movements of Ocean Water

Consider the following factors: 1. The shape of bays and estuaries has no influence on the magnitude of tides. 2. Presence of wide continental shelves. 3. Presence of mid-oceanic islands. Which of the above factors can influence the height or magnitude of tidal bulges?

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Which of the following best describes the general movement of warm ocean currents?

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With reference to the movements of ocean water, consider the following statements: 1. Ocean currents represent the horizontal motion of water while tides represent the vertical motion. 2. In waves, the water moves ahead from one place to another along with the wave train. 3. The upwelling of cold water from the subsurface is a form of horizontal motion. Which of the statements given above is/are correct?

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Consider the following statements regarding the characteristics of ocean waves: 1. The largest waves are typically found in open oceans rather than enclosed seas. 2. Steep waves are generally old and originate from far away places. 3. Slow and steady waves usually originate from far away places. Which of the statements given above is/are correct?

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The maximum height of a wave is determined by which of the following factors? 1. The strength of the wind has no role in determining wave height. 2. The duration for which the wind blows. 3. The area over which the wind blows in a single direction. Select the correct answer using the code given below:

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The correct option is Heating by solar energy causing water expansion..

Explanation

The variation in sea level across different latitudes is primarily influenced by the physical properties of seawater, specifically density changes driven by temperature.

Detailed Analysis:

Thermal Expansion: The equatorial region receives the most direct and intense solar insolation throughout the year. This results in significantly higher sea surface temperatures compared to the middle and high latitudes.
Volume Increase: As water warms, its density decreases, and it undergoes thermal expansion. This means that a column of warm water occupies a greater volume than an equivalent mass of cold water.
Sea Level Rise: Due to this expansion, the ocean surface at the equator stands approximately 8 cm higher than in the middle latitudes. This slight gradient contributes to the flow of ocean currents as water tends to flow down the slope.

Key Takeaway: Intense solar heating at the equator causes thermal expansion of seawater, resulting in a slightly higher sea level compared to cooler latitudes.