High Tide, Low Tide Archives

1. Consider the following statements with respect to ‘tides’: 1. The ti

Consider the following statements with respect to ‘tides’:

1. The tidal bulges on wide continental shelves have greater height.
2. When tides are channeled between islands, they are called tidal currents.

Which of the statements given above is/are correct?

1 only

2 only

Both 1 and 2

Neither 1 nor 2

This question was previously asked in

UPSC CBI DSP LDCE – 2023

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Both statements accurately describe phenomena related to tides: tidal bulges are amplified on wide continental shelves, and channeled tidal flows are called tidal currents.

Statement 1 is correct: As a tidal wave moves from the deep ocean onto a wide, shallow continental shelf, the decrease in water depth causes the wave height (and thus the tidal range) to increase due to a phenomenon called shoaling. The wide expanse of the shelf allows the tidal bulge to build up laterally. Statement 2 is correct: Tidal currents are the horizontal movement of water associated with the rise and fall of the tide. When these tidal flows are forced through narrow passages, such as between islands or in channels, their speed and strength increase, hence they are referred to as tidal currents, often becoming quite strong in these constricted areas.

The maximum height of tides is influenced by factors like the shape of the coastline, the depth of the water, and the configuration of bays and estuaries. Tidal currents are a significant force in coastal environments, affecting sedimentation, erosion, and navigation.

2. Tides occur in the oceans and seas due to which among the following?

Tides occur in the oceans and seas due to which among the following?

Gravitational force of the Sun
Gravitational force of the Moon
Centrifugal force of the Earth

Select the correct answer using the code given below.

1 only

2 and 3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2015

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Tides are primarily caused by the gravitational pull exerted by the Moon and the Sun on the Earth’s oceans. The gravitational force of the Moon is the dominant factor due to its closer proximity to Earth. Additionally, the centrifugal force resulting from the rotation of the Earth-Moon system around its common center of mass also contributes to tidal bulges on the side of Earth opposite to the Moon. Therefore, the gravitational forces of both the Sun and the Moon, along with the centrifugal force of the Earth’s rotation (within the Earth-Moon system), contribute to the occurrence of tides. All three statements are correct.

The primary forces causing tides are the gravitational attraction of the Moon and the Sun and the inertial (centrifugal) force of the Earth-Moon system.

The gravitational pull is strongest on the side of Earth facing the Moon, creating a bulge. On the opposite side, the centrifugal force (acting outwards from the center of the Earth-Moon system’s rotation) is relatively stronger than the Moon’s gravitational pull, creating another bulge. These bulges are the high tides. Low tides occur in the areas between the bulges. The Sun’s gravity also influences tides, causing spring tides (larger tides when the Sun, Moon, and Earth are aligned) and neap tides (smaller tides when the Sun and Moon are at right angles to each other relative to Earth).

3. Which one of the following statements is correct about Spring tides ?

Which one of the following statements is correct about Spring tides ?

High tide is higher than average high tide and Low tide is higher than average low tide.

High tide is lower than average high tide and Low tide is higher than average low tide.

High tide is higher than average high tide and Low tide is lower than average low tide.

High tide is lower than average high tide and Low tide is lower than average high tide.

This question was previously asked in

UPSC CAPF – 2023

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Spring tides occur when the Earth, Moon, and Sun are aligned (during New Moon and Full Moon). The combined gravitational pull of the Sun and Moon causes a greater tidal range than average. This results in high tides that are higher than the average high tide and low tides that are lower than the average low tide. Option C correctly describes this phenomenon. Option A describes a condition where both high and low tides are higher than average, which is incorrect as low tides are lower during spring tides. Options B and D incorrectly state that high tides are lower than average.

Spring tides are the tides with the largest tidal range, occurring during syzygy (alignment of Earth, Moon, and Sun) at New Moon and Full Moon, characterized by exceptionally high high tides and exceptionally low low tides.

Conversely, neap tides occur during the first and third quarter Moon phases, when the Moon and Sun are at right angles to the Earth. Their gravitational pulls partially cancel each other out, resulting in a smaller tidal range, with lower high tides and higher low tides than average.

4. The tides whose height is 20 percent more than normal tide are called

The tides whose height is 20 percent more than normal tide are called

spring tides

neap tides

apogean and perigean tides

daily and semi-diurnal tides

This question was previously asked in

UPSC CAPF – 2018

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Tides are influenced by the gravitational pull of the moon and the sun. The height of tides varies depending on the relative positions of the Earth, Moon, and Sun, as well as the Moon’s distance from Earth. Perigean tides occur when the moon is closest to the Earth (at perigee), resulting in stronger gravitational pull and consequently higher high tides and lower low tides than average. Apogean tides occur when the moon is farthest from the Earth (at apogee), resulting in weaker pull and lower high tides and higher low tides. The difference in tidal range between perigean and apogean tides can be significant, often cited around 20-40%. The phrasing “whose height is 20 percent more than normal tide” strongly suggests the influence of the Moon’s distance, pointing towards perigean tides, which are grouped with apogean tides in option C as distinct categories based on distance.

Tidal height variations are influenced by the alignment of the Earth, Moon, and Sun (causing spring and neap tides) and the Moon’s distance from Earth (causing perigean and apogean tides). Perigean tides are higher than average due to the Moon’s closer proximity.

Spring tides occur during new and full moons when the sun and moon are aligned with Earth, causing maximum tidal range (highest high tides, lowest low tides). Neap tides occur during quarter moons when the sun and moon are at right angles to Earth relative to the Earth, causing minimum tidal range. Perigean spring tides, occurring when a spring tide coincides with the moon being at perigee, result in exceptionally high tides.

5. If a place is affected by Tide at 6:00 AM Monday, normally at what tim

If a place is affected by Tide at 6:00 AM Monday, normally at what time the same place will be affected by Ebb ?

6:26 PM Monday

6:52 AM Tuesday

12:13 PM Monday

00:26 AM Tuesday

This question was previously asked in

UPSC CAPF – 2016

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The correct option is C) 12:13 PM Monday.

Tides follow a predictable pattern. In most places, there are two high tides and two low tides approximately every 24 hours and 50 minutes. The time between a high tide and the subsequent low tide (Ebb) is roughly half the period between two consecutive high tides, which is about 6 hours and 12.5 minutes. Ebb tide is the phase when the sea level is falling.

Given that high tide occurs at 6:00 AM Monday.
The low tide following this high tide will occur approximately 6 hours and 12.5 minutes later.
6:00 AM + 6 hours 12.5 minutes = 12:12:30 PM Monday.
The ebb tide is the period from high tide to low tide. The question asks “at what time the same place will be affected by Ebb?”. This is slightly ambiguous, as ebb is a period. However, among the options, 12:13 PM is the closest time to the predicted low tide, which marks the *end* of the ebb phase and the start of the flood phase. The other options represent subsequent high tide times. Therefore, 12:13 PM Monday is the most plausible answer representing the transition point following the ebb phase.

6. Tidal range denotes the :

Tidal range denotes the :

rise of sea water and its movement toward the coast

fall of sea water and its movement toward the sea

rise and fall of sea water due to gravitational forces

difference between high and low tide

This question was previously asked in

UPSC CAPF – 2009

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The correct option is D (difference between high and low tide).

– Tidal range is defined as the vertical difference between the sea level at high tide and the sea level at the subsequent low tide in a specific location.
– Statement A describes the flood tide.
– Statement B describes the ebb tide.
– Statement C describes the phenomenon of tides itself (the periodic rise and fall of sea water).
– Statement D accurately defines the tidal range.

Tidal ranges vary significantly depending on location, due to factors such as the shape of the coastline, water depth, and oceanic currents. Places like the Bay of Fundy in Canada have very high tidal ranges, while enclosed seas like the Mediterranean have very low ones.

7. The periodic rise and fall of ocean water in response to gravitational

The periodic rise and fall of ocean water in response to gravitational forces is called

Current

Waves

Tides

Tsunami

This question was previously asked in

UPSC NDA-2 – 2021

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Tides are the periodic rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth.

Gravitational forces from the Moon and Sun are the primary drivers of tides.

Ocean currents are continuous, directed movement of sea water. Waves are disturbances on the surface of water bodies. A tsunami is a series of large waves caused by earthquakes or other underwater disturbances.

8. Which of the following statements regarding neap tides is/are correct

Which of the following statements regarding neap tides is/are correct ?

1. It occurs every 14 – 15 days, which coincides with the first and third quarter of the Moon.
2. This tide has a small tidal range because the gravitational forces of the Moon and the Sun are in quadrature.

Select the answer using the code given below :

1 only

2 only

Both 1 and 2

Neither 1 nor 2

This question was previously asked in

UPSC NDA-1 – 2024

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Statements 1 and 2 are correct.

Neap tides occur twice a lunar month, during the first and third quarter Moon. At these times, the gravitational pull of the Sun is at a right angle to the gravitational pull of the Moon relative to Earth. This alignment causes the gravitational forces to partially cancel each other out, resulting in smaller differences between high and low tides, which is known as a smaller tidal range. This phenomenon occurs approximately every 14-15 days, halfway between spring tides.

Spring tides, which have the largest tidal range, occur during the new Moon and full Moon when the Sun, Earth, and Moon are aligned. Tidal range is the difference in height between high tide and low tide.

9. Which of the following positions of Sun, Earth and Moon is/are suitabl

Which of the following positions of Sun, Earth and Moon is/are suitable for Spring Tide ?

1. SYZYGY Conjunction
2. SYZYGY Opposition
3. Quadrature

Select the correct answer using the code given below :

1 only

2 only

1 and 2

1 and 3

This question was previously asked in

UPSC NDA-1 – 2023

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The correct answer is C) 1 and 2.

Spring tides are extreme tides (higher high tides and lower low tides) that occur when the gravitational forces of the Sun and Moon are aligned, reinforcing each other. This alignment happens when the Sun, Earth, and Moon are in a straight line, a configuration known as Syzygy. Syzygy occurs in two positions:
1. **Conjunction:** The Moon is between the Sun and the Earth (during the New Moon phase).
2. **Opposition:** The Earth is between the Sun and the Moon (during the Full Moon phase).
Quadrature occurs when the Moon is at a 90-degree angle relative to the Sun-Earth line (during the First and Third Quarter Moon phases), resulting in weaker tides known as neap tides.

The gravitational pull of both the Sun and the Moon affects Earth’s tides. When they pull in the same direction (Syzygy – Conjunction or Opposition), their effects combine, leading to spring tides. When they pull at right angles (Quadrature), their effects partially cancel out, leading to neap tides.

10. What is the time gap in occurrence of two successive tides at a given

What is the time gap in occurrence of two successive tides at a given place on the ocean surface?

12 hours

12 hours 26 minutes

24 hours

24 hours 52 minutes

This question was previously asked in

UPSC NDA-1 – 2019

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The time gap between the occurrence of two successive tides (e.g., two high tides or two low tides) at a given place on the ocean surface is approximately 12 hours and 26 minutes.

– Tides are primarily caused by the gravitational pull of the Moon and, to a lesser extent, the Sun.
– The Earth completes a rotation relative to the Sun in 24 hours (a solar day).
– However, the Moon also orbits the Earth in the same direction as Earth’s rotation. For a point on Earth to return to the same position relative to the Moon, it takes slightly longer than a solar day, approximately 24 hours and 50 minutes (a lunar day).
– There are usually two high tides and two low tides in one lunar day (semidiurnal tides).
– Therefore, the time between two successive high tides (or low tides) is about half a lunar day, which is approximately 12 hours and 25 minutes or 12 hours and 26 minutes.

The actual timing and amplitude of tides at any given location can be influenced by various factors, including the alignment of the Sun and Moon (leading to spring and neap tides), the shape of the coastline, and the depth of the water.