Physical Geography 4

Question 1

Hydrological cycle

Answer 1

The hydrological cycle, is the circulation of water within the earth’s hydrosphere in different forms i.e. the liquid, solid and the gaseous phases.

Question 2

Hydrosphere

Answer 2

The hydrosphere is the sum of all water on Earth, including water in the oceans, lakes, rivers, and in the air

Question 3

Distribution of water in different sources

Answer 3

71% oceanic 29% fresh water in glaciers and icecaps, groundwater sources, lakes, soil moisture, atmosphere, streams and within life.

Question 4

Oceans of the world

Answer 4

The geographers have divided the oceanic part of the earth into five oceans, namely the Pacific, the Atlantic, the Indian, Southern ocean and the Arctic.

Question 5

Major Oceanic relief/ division of ocean floor

Answer 5

four major divisions: (i) the Continental Shelf; (ii) the Continental Slope; (iii) the Deep Sea Plain; (iv) the Oceanic Deeps.

Question 6

Continental Shelf

Answer 6

1.area between the beach and shelf break, ends typically in a steep continental slope. The continental shelf is the extended margin of each continent occupied by relatively shallow seas and gulfs.
2.It is the shallowest part of the ocean showing an average gradient of 1° or even less.
3.The average width of continental shelves is about 80 km. almost absent or very narrow along some of the margins like the coasts of Chile, the west coast of Sumatra, etc. On the contrary, the Siberian shelf in the Arctic Ocean, the largest in the world,
4. The depth of the shelves also varies. 30m- 600 m.
5. The continental shelves are covered with variable thicknesses of sediments, and over a long time by the continental shelves, become the source of fossil fuels.

Question 7

Continental Slope

Answer 7

1.The continental slope connects the continental shelf and the ocean basins. It begins where the bottom of the continental shelf sharply drops off into a steep slope. Signifies end of continental plate and beginning of oceanic plate.
2.The gradient of the slope region varies between 2-5°. The depth of the slope region varies between 200 and 3,000 m.
3. Canyons and trenches are observed in this region.

Question 8

Deep Sea Plain

Answer 8

Deep sea plains are gently sloping areas of the ocean basins. These are the flattest and smoothest regions of the world. The depths vary between 3,000 and 6,000m. These plains are covered with fine-grained sediments like clay and silt.

Question 9

Oceanic Deeps or Trenches

Answer 9

These areas are the deepest parts of the oceans. The trenches are relatively steep sided, narrow basins. They are some 3-5 km deeper than the surrounding ocean floor. They occur at the bases of continental slopes and along island arcs and are associated with active volcanoes and strong earthquakes. Formed by convergent plates and subduction.

Question 10

Minor Relief Features

Answer 10

Ridges, hills, sea mounts, guyots, trenches, canyons, etc.

Question 11

Mid-Oceanic Ridges

Answer 11

A mid-oceanic ridge is composed of two chains of mountains separated by a large depression. The mountain ranges can have peaks as high as 2,500 m and some even reach above the ocean’s surface. Iceland, a part of the mid- Atlantic Ridge, is an example. Formed by floor spreading and cooling of lava.

Question 12

Seamount

Answer 12

It is a mountain with pointed summits, rising from the seafloor that does not reach the surface of the ocean. Seamounts are volcanic in origin. These can be 3,000-4,500 m tall. Often the vents of volcanoes. The Emperor seamount, an extension of the Hawaiian Islands in the Pacific Ocean, is a good example.

Question 13

Submarine Canyons

Answer 13

These are deep valleys, some comparable to the Grand Canyon of the Colorado river. They are sometimes found cutting across the continental shelves and slopes, often extending from the mouths of large rivers. The Hudson Canyon is the best known submarine canyon in the world.

Question 14

Guyots

Answer 14

It is a flat topped seamount. They show evidences of gradual subsidence through stages to become flat topped submerged mountains. It is estimated that more than 10,000 seamounts and guyots exist in the Pacific Ocean alone.

Question 15

Atoll

Answer 15

These are low islands found in the tropical oceans consisting of coral reefs surrounding a central depression. It may be a part of the sea (lagoon), or sometimes form enclosing a body of fresh, brackish, or highly saline water.

Question 16

Factors Affecting Temperature Distribution of oceans

Answer 16

The process of heating and cooling of the oceanic water is slower than land.
(i) Latitude:the temperature of surface water decreases from the equator towards the poles because the amount of insolation decreases poleward.
(ii) Unequal distribution of land and water : the oceans in the northern hemisphere receive more heat due to their contact with larger extent of land than the oceans in the southern hemisphere.
(iii) Prevailing Wind:the winds blowing from the land towards the oceans drive warm surface water away form the coast resulting in the upwelling of cold water from below. It results into the longitudinal variation in the temperature. Contrary to this, the onshore winds pile up warm water near the coast and this raises the temperature.
(iv) Ocean currents : warm ocean currents raise the temperature in cold areas while the cold currents decrease the temperature in warm ocean areas.

Question 17

Thermocline

Answer 17

Boundary separating surface water from deeper waters and there is a rapid fall of temperature below it. 90% water below thermocline.

Question 18

Vertical Distribution of Temperature

Answer 18

Temperature of ocean and middle and low latitudes is 3 tiered.
1. 0-500m with temperature 20-25 degrees, always present in tropical region but in mid latitude only in summer
2. Thermocline layer 500-1000 m- rapidly decreasing temperature
3. Very cold, with temperature upto 0 degrees
In High latitudes i.e. polar region, water from surface to bottom 0 degrees.

Question 19

Horizontal distribution of Temperature

Answer 19

Average temperature 27 degrees, decreases from equator to poles. The oceans in the northern hemisphere record relatively higher temperature than in the southern hemisphere. The highest temperature is not recorded at the equator but slightly towards north of it. All this due to uneuqual distribution of land and water. The average annual temperatures for the northern and southern hemisphere are around 19° C and 16° C respectively.

Question 20

Salinity

Answer 20

amount of salt (in gm) dissolved in 1,000 gm (1 kg) of seawater. It is usually expressed as parts per thousand (o/oo) or ppt.

Question 21

Factors affecting ocean salinity-

Answer 21

(i) The salinity of water in the surface layer of oceans depends mainly on evaporation and precipitation.
(ii) Surface salinity is greatly influenced in coastal regions by the freshwater flow from rivers, and in polar regions by the processes of freezing and thawing of ice.
(iii) Wind, also influences salinity of an area by transferring water to other areas.
(iv) The ocean currents contribute to the salinity variations. Salinity, temperature and density of water are interrelated. Hence, any change in the temperature or density influences the salinity of water in an area.

Question 22

HORIZONTAL DISTRIBUTION OF SALINITY

Answer 22

The salinity for normal open ocean ranges between 33 o/oo and 37 o/oo.
1. The salinity variation in the Pacific Ocean is mainly due to its shape and larger areal extent. Salinity decreases on the western parts of the northern hemisphere because of the influx of melted water from the Arctic region. In the same way in the south, it decreases.
2. The average salinity of the Atlantic Ocean is around 36 o/oo. Sub tropical region with high evaporation, low rainfall. The North Sea, in spite of its location in higher latitudes, records higher salinity due to more saline water brought by the North Atlantic Drift. The Mediterranean Sea records higher salinity due to high evaporation. Baltic Sea, Black Sea records low salinity due to influx of river waters in large quantity.
3. The average salinity of the Indian Ocean is 35 o/oo. The low salinity trend is observed in the Bay of Bengal due to influx of river water. On the contrary, the Arabian Sea shows higher salinity due to high evaporation and low influx of fresh water.

Question 23

Vertical Distribution of Salinity

Answer 23

Salinity changes with depth, increases. The lower salinity water rests above
the higher salinity dense water. At the surface changes because of 4 factors discussed previously.

Question 24

Halocline

Answer 24

Point in ocean after which salinity sharply increases.

Question 25

Types of movement of ocean water

Answer 25

Horizontal (currents and waves), vertical (tides)

Question 26

Ocean currents and waves define with difference

Answer 26

continuous flow of huge amount of water in a definite direction while the waves are the horizontal motion of water. Water moves ahead from one place to another through ocean currents while the water in the waves does not move, but the wave trains move ahead.

Question 27

Waves and what causes?

Answer 27

A wave is a disturbance in a medium because of energy without a net movement of particles. Waves are actually the energy, not the water as such, which moves across the ocean surface. Water particles only travel in a small circle as a wave passes. Formed due to pushing of wind and the pull of gravity.

Question 28

Wave crest and trough

Answer 28

The highest and lowest points of a wave are called the crest and trough respectively.

Question 29

Wave height

Answer 29

It is the vertical distance from the bottom of a trough to the top of a crest of a wave.

Question 30

Wave amplitude

Answer 30

It is one-half of the wave height.

Question 31

Wave period

Answer 31

It is merely the time interval between two successive wave crests or troughs as they pass a fixed point.

Question 32

Wavelength

Answer 32

Wave speed

Question 33

Wave frequency

Answer 33

It is the number of waves passing a given point during a one- second time interval.

Question 34

Tides and what causes

Answer 34

The periodical rise and fall of the sea level, once or twice a day, mainly due to the attraction of the sun and the moon, is called a tide. Movement of water caused by meteorological effects (winds and atmospheric pressure changes) are called surges.

Question 34

A wave’s size and shape reveal its origin. Explain

Answer 34

Steep waves are fairly young ones and are probably formed by local wind. Slow and steady waves originate from far away places, possibly from another hemisphere.

Question 35

Surges

Answer 35

Movement of water caused by meteorological effects (winds and atmospheric pressure changes) are called surges. Surges not by tides.

Question 36

tide-generating force

Answer 36

he difference between these two forces; i.e. the gravitational attraction of the moon and the centrifugal force.

Question 37

tidal currents

Answer 37

When the tide is channelled between islands or into bays and estuaries they are called tidal currents.

Question 38

Effect of relief on tides

Answer 38

The tidal bulges on wide continental shelves, have greater height. When tidal bulges hit the mid-oceanic islands they become low. The shape of bays and estuaries along a coastline can also magnify the intensity of tides. Funnel-shaped bays greatly change tidal magnitudes.

Question 39

Types of Tides

Answer 39

Tides based on Frequency, Tides based on the Sun, Moon and the Earth Positions

Question 40

Tides based on the Sun, Moon and the Earth Positions

Answer 40

Spring tides : The position of both the sun and the moon in relation to the earth has direct bearing on tide height. When the sun, the moon and the earth are in a straight line, the height of the tide will be higher. These are called spring tides and they occur twice a month, one on full moon period and another during new moon period
Neap tides : Normally, there is a seven day interval between the spring tides and neap tides. At this time the sun and moon are at right angles to each other and the forces of the sun and moon tend to counteract one another. The Moon’s attraction, though more than twice as strong as the sun’s, is diminished by the counteracting force of the sun’s gravitational pull.

Question 41

Tides during perigee, perihelion, apogee, aphelion

Answer 41

Max height for perigee, perihelion and least for apogee, aphelion

Question 42

Ebb and flow

Answer 42

The time between the high tide and low tide, when the water level is falling, is called the ebb. The time between the low tide and high tide, when the tide is rising, is called the flow or flood.

Question 43

Tides based on Frequency

Answer 43

Semi-diurnal tide : The most common tidal pattern, featuring two high tides and two low tides each day. The successive high or low tides are approximately of the same height.
Diurnal tide : There is only one high tide and one low tide during each day. The successive high and low tides are approximately of the same height.
Mixed tide : Tides having variations in height are known as mixed tides. These tides generally occur along the west coast of North America and on many islands of the Pacific Ocean.

Question 44

Importance of Tides

Answer 44

1. Help in navigation
2. Remove pollutants and circulate nutrients of ocean plants
3. Help generate electricity in Canada, France, Russia, and China. Gulf of Kutch R&D phase.

Question 44

Ocean currents

Answer 44

Ocean currents are like river flow in oceans. They represent a regular volume of water in a definite path and direction.

Question 45

Forces influencing ocean currents

Answer 45

1. Temperature- affects density- warmer less dense
2. Salinity- affects density- cold more saline and dense and sinks
3. Wind
4. Coriolis forces
5. Ocean relief

Question 46

Types of Ocean Currents

Answer 46

based on their depth, based on temperature

Question 46

Ocean currents based on depth

Answer 46

(i) surface currents constitute about 10 per cent of all the water in the ocean, these waters are the upper 400 m of the ocean; (ii) deep water currents make up the other 90 per cent of the ocean water. These waters move around the ocean basins due to variations in the density and gravity.

Question 47

Ocean currents based on temperature and where are they found

Answer 47

(i) cold currents bring cold water into warm water areas. These currents are usually found on the west coast of the continents in the low and middle latitudes (true in both hemispheres) and on the east coast in the higher latitudes in the Northern Hemisphere; (ii) warm currents bring warm water into cold water areas and are usually observed on the east coast of continents in the low and middle latitudes (true in both hemispheres). In the northern hemisphere they are found on the west coasts of continents in high latitudes.
East west orientation due to coriolis force generated winds- easterlies, westerlies.

Question 48

Major Ocean Currents pattern

Answer 48

The oceanic circulation pattern roughly corresponds to the earth’s atmospheric circulation pattern. The oceanic circulation transports heat from one latitude belt to another in a manner similar to the heat transported by the general circulation of the atmosphere. The cold waters of the Arctic and Antarctic circles move towards warmer water in tropical and equatorial regions, while the warm waters of the lower latitudes move polewards.

Question 49

Effects of Ocean Currents

Answer 49

1. Influence climate- warm/cold (ENSO eg)
2. mixing of warm and cold currents help to replenish the oxygen and favour the growth of planktons, the primary food for fish population. The best fishing grounds of the world exist mainly in these mixing zones.

Question 50

Ocean Mean Temperature

Answer 50

OMT, which is measured up to a depth of 26 degree C isotherm, is more stable and consistent, and the spatial spread is also less. The 26 degree C isotherm is seen at depths varying from 50–100 metres. During January–March, the mean 26 degree C isotherm depth in the Southwestern Indian Ocean is 59 metres.
OMT is analysed by measuring the ocean thermal energy during the period from January to March. 80% success rate.

Question 51

Sea surface temperature (SST)

Answer 51

routinely used for predicting whether the total amount of rainfall that India receives during the monsoon season will be less or more than the long-term mean of 887.5 mm. 60% success rate. Sea surface temperature gives information only about the thin upper layer of the ocean and does not reflect the thermal energy available in the upper ocean, also has wild fluctuations.

Question 52

Lagrangian points

Answer 52

Points where gravity of two bodies cancels out each other

Question 53

Trojan asteroids

Answer 53

Trojan asteroids are asteroids that share an orbit with a planet and are located at the leading (L4) and trailing (L5) Lagrangian points.

Question 54

Antarctic overturning circulation

Answer 54

Overturning circulation is a large-scale pattern of ocean currents that moves water around the globe. It’s often referred to as the global conveyor belt because it transports heat, oxygen, nutrients, and carbon dioxide throughout the ocean. Antarctica plays an important role in feeding cold nutrition rich water, but getting disrupted due to climate change which itself is causing more climate change.

Question 55

Oceanic cold waves

Answer 55

Winds and currents force coastal waters to move offshore, which are then replaced from below by cold water from the deep ocean. This process is known as upwelling. Climate change disrupting this, causing Surface temperatures can plummet rapidly — by 10ºC or more over a day or two. When these conditions persist for several days or weeks, the area experiences a “coldwave”, causing marine deaths.

Question 56

belt of calm near equator

Answer 56

intertropical Convergence Zone (ITCZ). It’s a region of low pressure where the trade winds from the Northern and Southern Hemispheres converge.

Question 57

Estuaries

Answer 57

where rivers meet oceans, known as estuaries, fishing can be highly productive

Question 58

Exfoliation means

Answer 58

when the surface layers of rock peel away due to PHYSICAL weathering. not chemical.

Question 59

solilfluction

Answer 59

flow of water saturated soil down a sleep slope under pull of gravity. soil opened and weakened by frost most susceptible. moevement few inches per day.

Question 60

Inselbergs and monadnocks

Answer 60

Inselbergs are often formed in arid or semi-arid climates where there is little vegetation to protect the rock from erosion while monadnocks in humid areas.

Question 61

subsidence vs uplift

Answer 61

sinking vs rising of land

Question 62

Aeolian landscape means

Answer 62

related to wind i.e. erosion, transportation, deposition

Question 63

tombolo

Answer 63

when a spit joins an island to mainland

Question 64

spit

Answer 64

narrow coastal land formation that is tied to the coast at one end.

Question 65

Infrared radiation

Answer 65

is a type of electromagnetic radiation that is invisible to the human eye. Its wavelengths are longer than that of visible light. It is often associated with heat because it is emitted by objects based on their temperature. Warmer objects emit more infrared radiation.

Question 66

How do clouds actually contribute to earth’s warming? Low and high

Answer 66

Whether a given cloud will heat or cool the surface depends on several factors, including the cloud’s altitude, its size, and the make-up of the particles that form the cloud.
STRATOCUMULUS- Low, thick clouds primarily reflect solar radiation and cool the surface of the Earth. CIRRUS- High, thin clouds primarily transmit incoming solar radiation; at the same time, they trap some of the outgoing infrared radiation emitted by the Earth and radiate it back downward, thereby warming the surface of the Earth. Usually, the higher a cloud is in the atmosphere, the colder its upper surface and the greater is its cloud greenhouse forcing.

Question 67

Discuss the albedo and greenhouse forcing of deep convective i.e. cumulonimbus clouds

Answer 67

As a consequence, overall, the cloud greenhouse and albedo forcings almost balance, and the overall effect of cumulonimbus clouds is neutral-neither warming nor cooling.

Question 68

Overall net effect of clouds wrt insolation

Answer 68

Overall, clouds have the effect of lessening the amount of heating that would otherwise be experienced at Earth’s surface

Question 69

Different parts of the Earth have different albedos. Explain.

Answer 69

Ocean surfaces and rain forests have low albedos, which means that they reflect only a small portion of the sun’s energy. Deserts, ice, and clouds, however, have high albedos; they reflect a large portion of the sun’s energy.

Question 70

Approx albedo of the earth

Answer 70

Over the whole surface of the Earth, about 30 percent of incoming solar energy is reflected back to space.

Question 71

cloud albedo forcing

Answer 71

cloud reflects more shortwave radiation back to space than the surface would in the absence of the cloud, thus leaving less solar energy available to heat the surface and atmosphere. Taken by itself net negative.

Question 72

“cloud greenhouse forcing”

Answer 72

the process by which clouds absorb and reemit longwave radiation emitted by the Earth, which warms the Earth. and, taken by itself, tends to cause a heating or “positive forcing” of the Earth’s climate.

Question 73

Discuss in terms of temperature and ocean currents, latitude wise, which edges of continents will be warmer-East/west?

Answer 73

In low and middle latitudes, due to easterlies, warm water is taken from east to west, making west coasts of continents warmer and eastern colder. In the higher latitudes, westerlies take warmer water from west to east making eastern edges of continents warmer and western colder,

Question 74

Jet streams

Answer 74

4 bands of high winds flowing west to east (due to easterly rotation of earth) 6-11 km high in troposphere, 320 km/h speed. Formed at polar and sub tropical regions due to convergence of cold and warm air masses

Question 75

Eye of cyclone

Answer 75

Area of low pressure, high temperature (above 28 degrees), no rainfall (dry), calm winds of not more than 24 km/h . Only tropical cyclones have eyes. In temperate cyclones there is no single place where winds are inactive.