Which one of the following is the tide produced as a consequence of moon and sun pulling the earth in the same direction ?

1. Introduction to Tides: Gravitational and Centrifugal Forces (basic)

Welcome to your first step in mastering ocean water properties! To understand the ocean, we must first understand its rhythm. Tides are the periodical rise and fall of the sea level, occurring once or twice a day. While they might look like waves, they are fundamentally different: whereas waves are driven by wind, tides are primarily driven by the celestial dance of the Earth, Moon, and Sun Fundamentals of Physical Geography, NCERT 2025, Chapter 13, p.109.

The magic of tides lies in the tug-of-war between two opposing forces. The first is gravitational attraction. The Moon, being our closest neighbor, exerts a powerful pull on Earth's waters; the Sun also pulls, but its effect is less due to its immense distance. The second is centrifugal force, which is the outward force created by the Earth's rotation and its orbital movement. The actual tide-generating force is the mathematical difference between these two Physical Geography, PMF IAS, Chapter 32, p.501.

This interaction creates two distinct "bulges" of water on Earth simultaneously:

• The Near Side: On the side of the Earth facing the Moon, the Moon's gravitational pull is at its strongest. Since this pull exceeds the centrifugal force, the water is drawn toward the Moon, creating a high-tide bulge.
• The Far Side: On the side opposite the Moon, the gravitational pull is weaker due to the distance. Here, the centrifugal force dominates, pushing the water outward and creating a second high-tide bulge Fundamentals of Physical Geography, NCERT 2025, Chapter 13, p.109.

Because the Earth rotates, a specific location on the coast will pass through these bulges and the depressions between them, resulting in the high and low tides we observe. Because these movements are based on predictable planetary positions, we can calculate and forecast tides well in advance for navigators and fishermen Physical Geography, PMF IAS, Chapter 32, p.506.

Sources: Fundamentals of Physical Geography, NCERT 2025, Chapter 13: Movements of Ocean Water, p.109; Physical Geography, PMF IAS, Chapter 32: Ocean Movements Ocean Currents And Tides, p.501; Physical Geography, PMF IAS, Chapter 32: Ocean Movements Ocean Currents And Tides, p.506

2. Classification of Tides based on Frequency (basic)

When we study tides, one of the most fundamental ways to categorize them is by their frequency—essentially, how many high and low tides occur within a 24-hour period. While we often imagine tides as a simple twice-a-day occurrence, the reality varies across the globe due to the shape of coastlines and the depth of ocean basins. The most common pattern is the Semi-diurnal tide, where a coastal area experiences two high tides and two low tides every day. In this pattern, the successive high or low tides are roughly the same height FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 13: Movements of Ocean Water, p.110.

In some regions, the geography of the ocean floor or the coast limits this frequency to a Diurnal tide. Here, you will find only one high tide and one low tide during each day. Similar to semi-diurnal tides, the heights of the successive tides in a diurnal cycle remain relatively consistent Physical Geography by PMF IAS, Chapter 32: Ocean Movements Ocean Currents And Tides, p.503. However, nature often gives us a blend of these two, known as Mixed tides. In a mixed tidal pattern, there are typically two high and two low tides, but they have variations in height—for instance, one high tide might be significantly higher than the other. This complexity is common along the west coast of North America and many Pacific islands FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 13: Movements of Ocean Water, p.110.

It is fascinating to note that local geography can create unique anomalies. For example, Southampton in the UK can experience 6 to 8 tidal events a day because it receives water from both the North Sea and the English Channel at different intervals Physical Geography by PMF IAS, Chapter 32: Ocean Movements Ocean Currents And Tides, p.502. Understanding these frequencies is vital for navigation, fishing, and coastal management, as it dictates the rhythm of life at the water's edge.

Tide Type	Frequency (per day)	Height Characteristics
Semi-diurnal	2 High, 2 Low	Successive tides are almost equal in height.
Diurnal	1 High, 1 Low	Successive tides are almost equal in height.
Mixed	2 High, 2 Low	Successive tides have varying/different heights.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Chapter 13: Movements of Ocean Water, p.110; Physical Geography by PMF IAS, Chapter 32: Ocean Movements Ocean Currents And Tides, p.502-503

3. Ocean Currents: Drivers and Patterns (intermediate)

Imagine the ocean not as a static pool, but as a massive, multi-layered conveyor belt that never stops. To understand how this water moves, we categorize the drivers into two groups: Primary Forces, which initiate the movement, and Secondary Forces, which influence the direction and vertical flow of the water Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.486.

The movement starts with solar heating. Because the Sun heats the Earth unevenly, water near the equator expands and becomes slightly less dense, making the sea level there about 8 cm higher than in the middle latitudes. This creates a very subtle slope that allows water to flow downward under the influence of gravity. Simultaneously, wind blowing across the surface creates friction, dragging the top layers of water along with it. Once the water is in motion, the Coriolis Force (caused by Earth's rotation) steps in; it doesn't start the current, but it deflects it—to the right in the Northern Hemisphere and to the left in the Southern Hemisphere—creating the giant circular patterns we call gyres Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.487.

While wind dominates the surface (the top 10% of the ocean), the deep ocean (the other 90%) moves due to density differences. This is where secondary forces like temperature and salinity come into play. Cold water and highly saline water are denser and heavier, causing them to sink, while warmer or fresher water stays near the surface. This creates a vertical movement known as thermohaline circulation. Interestingly, while salinity is the master of vertical currents, its impact on horizontal movement is relatively minor Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.489.

Force Category	Key Drivers	Primary Role
Primary Forces	Solar heating, Wind, Gravity, Coriolis Force	Initiate movement and horizontal direction.
Secondary Forces	Temperature and Salinity differences	Drive vertical movement and density-based flow.

Sources: Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.486; Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.487; Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.489

4. Ocean Salinity and Temperature Distribution (intermediate)

Understanding the distribution of ocean temperature and salinity is like learning the "anatomy" of the seas. These two factors are not just numbers; they dictate the movement of massive water masses and influence global climates. Broadly, these properties vary both horizontally (across the surface) and vertically (with depth).

Temperature Distribution is primarily governed by the amount of solar energy or insolation received. Horizontally, surface temperatures decrease from the equator toward the poles as the sun's rays become more slanted FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Water (Oceans), p.103. However, it’s not a simple gradient. The unequal distribution of land and water plays a role; for instance, the Northern Hemisphere’s oceans are generally warmer because they are in contact with larger landmasses that radiate heat. Additionally, prevailing winds can push warm surface water away from a coast, causing upwelling—the rising of cold, nutrient-rich water from the depths—which significantly cools the local sea surface FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Water (Oceans), p.103.

Salinity Distribution is a bit more complex. On the surface, it is a tug-of-war between evaporation (which removes water and leaves salt behind, increasing salinity) and precipitation (which adds fresh water, decreasing salinity) FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Water (Oceans), p.104. In the open ocean, salinity typically ranges between 33 and 37 parts per thousand Physical Geography by PMF IAS, Ocean temperature and salinity, p.519. In polar regions, the freezing of sea ice increases salinity in the remaining liquid water, while the thawing (melting) of ice adds fresh water and lowers it.

Property	Horizontal Drivers	Vertical Behavior
Temperature	Latitude, Land-water ratio, Ocean currents	Decreases with depth; sharp drop at the Thermocline.
Salinity	Evaporation vs. Precipitation, River influx	Generally increases with depth; sharp rise at the Halocline.

The most fascinating aspect is how these properties interact to create stratification. Denser water—which is usually colder and saltier—naturally sinks below lighter, fresher water FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Water (Oceans), p.106. This leads to the formation of the Halocline, a distinct zone where salinity increases sharply with depth Physical Geography by PMF IAS, Ocean temperature and salinity, p.520. While salinity generally increases with depth because saltier water is heavier, local variations exist: at the equator, heavy rainfall makes the surface water less salty than the water immediately beneath it.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Water (Oceans), p.103; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Water (Oceans), p.104; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Water (Oceans), p.106; Physical Geography by PMF IAS, Ocean temperature and salinity, p.519; Physical Geography by PMF IAS, Ocean temperature and salinity, p.520

5. Tidal Variation: Perigee, Apogee, Perihelion and Aphelion (intermediate)

While we often focus on the alignment of the Sun and Moon to explain tides (the Spring and Neap cycles), there is a second critical factor: distance. Because the orbits of the Moon around the Earth, and the Earth around the Sun, are elliptical rather than perfectly circular, the gravitational pull acting on our oceans fluctuates as these distances change.

Let’s start with the Moon, our primary tide-maker. Once a month, the Moon reaches its point of closest approach to Earth, known as Perigee. During this phase, the Moon's gravitational pull is at its strongest, resulting in unusually high and low tides—essentially a much greater tidal range than normal. Approximately two weeks later, the Moon reaches Apogee, its farthest point from Earth. At this distance, the gravitational force is significantly reduced, and the resulting tidal ranges are much lower than average Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.506.

The Sun’s distance from Earth also plays a role through the Perihelion and Aphelion cycles. On or around January 3rd each year, the Earth is at its closest point to the Sun, or Perihelion. This proximity slightly boosts the Sun's gravitational influence, leading to unusually high tidal ranges. Conversely, around July 4th, the Earth is at its farthest point, known as Aphelion, which leads to tidal ranges that are much less than average FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI, Movements of Ocean Water, p.110. For a civil services aspirant, it is vital to remember that these variations in distance can either amplify or dampen the standard Spring and Neap tide cycles depending on when they occur.

Position	Body Involved	Distance Status	Effect on Tidal Range
Perigee	Moon	Closest to Earth	Greater than normal range
Apogee	Moon	Farthest from Earth	Less than average range
Perihelion	Sun	Closest to Earth (Jan)	Unusually high range
Aphelion	Sun	Farthest from Earth (July)	Unusually low range

Sources: Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.506; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Movements of Ocean Water, p.110-113

6. Syzygy and Quadrature: Celestial Alignment (exam-level)

To understand why some tides are massive while others are quite mellow, we have to look at the geometry of our solar system. The relative positions of the Sun and the Moon in relation to the Earth determine the strength of the tidal pull. There are two primary celestial configurations you must master: Syzygy and Quadrature.

1. Syzygy (Spring Tides): This term refers to a configuration where the Sun, Moon, and Earth are aligned in a straight line. This happens twice a month. During a New Moon, the Sun and Moon are on the same side of the Earth (conjunction), pulling the oceans in the same direction. During a Full Moon, they are on opposite sides (opposition), but their gravitational pulls still act along the same axis Science Class VIII NCERT, Keeping Time with the Skies, p.175. In both cases, the solar tide reinforces the lunar tide. The result is Spring Tides—where high tides are exceptionally high and low tides are very low, creating the maximum tidal range Fundamentals of Physical Geography NCERT Class XI, Movements of Ocean Water, p.110.

2. Quadrature (Neap Tides): About seven days after the spring tide, the Moon reaches its first and third quarter phases. Here, the Sun and Moon are at right angles (90°) to each other relative to the Earth. This position is called Quadrature. Because they are pulling in different directions, the Sun's gravitational pull partially offsets the Moon's pull Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.504. This leads to Neap Tides, characterized by a much smaller tidal range—the high tides aren't very high, and the low tides aren't very low.

To help you compare these two states, let's look at their key differences:

Feature	Syzygy (Spring Tide)	Quadrature (Neap Tide)
Alignment	Straight line (180°)	Right angle (90°)
Lunar Phase	New Moon or Full Moon	First or Third Quarter
Tidal Range	Maximum (Very high/Very low)	Minimum (Moderate tides)

Sources: Fundamentals of Physical Geography NCERT Class XI, Movements of Ocean Water, p.110; Physical Geography by PMF IAS, Ocean Movements Ocean Currents And Tides, p.504; Science Class VIII NCERT, Keeping Time with the Skies, p.175

7. Solving the Original PYQ (exam-level)

Now that you have mastered the fundamental mechanics of gravitational pull, this question asks you to apply the concept of linear alignment, or syzygy. When you studied the positions of celestial bodies, you learned that the Sun and Moon act like magnets on Earth's oceans. In this specific scenario—the New Moon phase—the Sun and Moon are positioned on the same side of the Earth. According to FUNDAMENTALS OF PHYSICAL GEOGRAPHY (NCERT), this means their gravitational forces are not competing but are additive, pulling the water in the same direction to create a massive tidal bulge.

To arrive at the correct answer, you must distinguish between the state of a tide and the type of tide. While the combined pull creates a very high tide, the technical term for this phenomenon of maximum tidal range (highest highs and lowest lows) is the Spring tide. As emphasized in Physical Geography by PMF IAS, this occurs twice a month when the Earth, Sun, and Moon are in a straight line. Therefore, (A) Spring tide is the correct classification for the tide produced when these forces work in unison.

UPSC often includes High tide and Low tide as distractors to test if you can distinguish between a daily occurrence and an astronomical event. High and low tides happen every day due to Earth's rotation, regardless of whether the Sun and Moon are aligned. On the other hand, Neap tide is the exact opposite trap; it occurs during quadrature, when the Sun and Moon pull at right angles, partially canceling each other's force. By identifying that the question specifies "pulling in the same direction," you can confidently eliminate the weaker Neap tides and the generic daily cycles to choose Spring tide.