The document discusses various topics related to oceanography including ocean bottom relief, islands, coral reefs, coral bleaching, movement of ocean water through waves, currents and tides, and salinity of ocean water. It provides details on factors influencing ocean currents like rotation of Earth, air pressure, density gradients, and Coriolis force. Types of islands like continental, volcanic, coral and sandbar are described along with examples. Formation and types of coral reefs as well as conditions for coral growth are summarized.

1. oceanography
the study of the physical and biological aspects
of the ocean. It is an Earth science, which covers
a wide range of topics ,
including ecosystem dynamics; ocean
currents, waves, plate tectonics and the geology
of the sea floor.

2. Topics under Oceanography
Ocean Bottom Relief
Ocean Currents
Ocean Tide
Salinity of Ocean water
Coral Reef

3. Ocean Bottom Relief
• Oceanic crust –first order relief – most
fundamental –basaltic
• Oceanic crust thickness = 1-3 km, higher density
• Oceanic crust created at MOR and destroyed at
trenches
• Ocean floor is not flat. More diversity than on
continents

4. Ocean Bottom Relief

5. Ocean-Continent margins

6. Islands
• An island or isle is any piece of sub-
continental land that is surrounded by water
• types of island-continental, volcanic, coral,
sandbar island

7. Island Formation
continental Once part of large
continent
volcanic O-O plate
collision, Hot spot
coral Formed due to
coral reefs
Sand-bar island Accumulation of
sand near coast

8. Example of Islands
Volcanic Continent
al
Coral Sandbar
Japan Shri Lanka Lakshadwe
ep
Long
Island
(New
York)
Philippin
es
Madagasc
ar
Maldives
Kurile Vancouver Mauritius
Aleutian Baffin
Island
Bahama,
Bermuda

9. Coral Reefs
•Indicative of
health of Marine
ecology
•Primary food-
chain
•Source of great
biodiversity

10. Coral Reefs
• Corals = tiny fleshy sea anemones polyps.
• They extract Ca from the sea water for
their skeletons to protect their bodies.
• One generation die on previous
generation.
• Corals live symbiotic relationship with
microscopic plant – Zooxanthalae,
photosynthesis capabilities.
• Zooxanthalae provide food to corals and
corals provide protection to zooxanthalae

11. Formation of coral reef
• Corals can be
developed both at
the margins of the
continents or
around islands
• Types of coral
reefs
1) Fringing reef
2) Barrier reef
3) Atoll

12. Condition for growth of Corals
• Need submarine shallow platform (50
meter deep)– to receive sun light
• Temperature- 25-27 degree
• Warm, tropical and low latitude waters
• Salinity – 33 ppt
• Not at mouth of river, No turbulent water
• Need circulating nutrient rich water

13. Coral Bleaching
• When corals
are stressed by changes
in conditions such as
temperature, light, or
nutrients, they expel the
symbiotic algae living in
their tissues, causing
them to turn completely
white

14. Reason of coral Bleaching
• Global warming => increase in sea surface
temperature
• Ozone depletion => increase in solar
irradiation
• Ocean acidification
• algal bloom
• Increase sedimentation from rivers
• Marine pollution – oil spill
• Diseases

15. Movement of ocean water
• Waves
• currents
• Tides

16. waves
Waves are the forward movement of ocean
waters which are created by the friction
between wind and surface water.
Creation of waves:
• wind pushes the water body due to friction
creating crests.
• gravity pulls the crests of the waves
downward, the falling water pushes the
former troughs upward.

17. Ocean Currents
• Ocean currents are narrow and
shallow (up to 500 meter deep),
stream of water circulating along the
Ocean margins
• Circumnavigate the earth

19. Wind- global (planetary winds)
Temp and salinity (vertical mobility)
Gravity
Coriolis Force
Forces responsible for Ocean
Current

20. GRAVITY
• Water moves from high sea levels to
low sea level due to gravity
• differential Gravitational pull : gravity
pull is more at poles than equator
region – water move from equator to
polar regions

21. temperature gradient
• Water expands under high temperature
and gets lighter which increases sea level.
• Surface Water moves from equator to pole
• Cold water is heavier (denser) and hence
sinks downward.
• Cold water from pole flow towards equator
at subsurface level, to balance loss of water
at equator

22. Salinity gradient
• High Salinity increases density of water and
Denser water sinks down making the sea level
lower. Similarly lesser salinity decreases the
density of water and eventually the sea level
gets high.
• Hence surface water move from low saline area
towards high saline area i.e from polar region to
equator region.
• At subsurface level water moves from High saline
area towards less saline area.

23. influence of wind (atmospheric
circulation)
• Wind blowing on the surface of the ocean
pushes the water to move. Friction between
the wind and the water surface affects the
movement of the water body in its course.
• Winds are responsible for both magnitude and
direction [Coriolis force also affects direction] of
the ocean currents. Example: Monsoon
winds are responsible for the seasonal reversal
of ocean currents in the Indian ocean

24. Influence of Coriolis force
• The Coriolis force intervenes and
causes the water to move to
the right in the northern hemisphere
and to the left in the southern
hemisphere.

25. Coriolis force
• an effect whereby a mass moving in a rotating
system experiences a force acting perpendicular to
the direction of motion and to the axis of rotation.
On the earth, the effect tends to deflect moving
objects to the right in the northern hemisphere
and to the left in the southern hemisphere.

27. UPSC 2012
Q. Consider the following factors:
1. Rotation of the earth
2. Air pressure and wind
3. Density of ocean water
4. Revolution of the earth
Which of the above factors influence ocean currents?
a) 1 and 2
b) 1,2,3
c) 1 and 4
d) 2,3,4

28. Ans. B)
Rotation of the earth -> coriolis force
Air pressure and wind -> planetary winds
Density of water -> salinity

29. Q. How ocean currents originate?
Discuss how ocean currents impact
trade and commerce.

30. Ocean tide
• 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
• Causes:
• The moon’s gravitational pull to a great
extent and to a lesser extent the sun’s
gravitational pull
• Another factor is centrifugal force which acts
opposite to gravitational pull of earth.
• Tides occur due to a balance between all these
forces.

32. Factors Controlling the Nature and
Magnitude of Tides
• The movement of the moon in relation to the
earth.
• Changes in position of the sun and moon in
relation to the earth.
• Uneven distribution of water over the globe.
• Irregularities in the configuration of the oceans.
• The tidal bulges on wide continental shelves,
have greater height. When tidal bulges hit the
mid-oceanic islands they become low.

33. • The shape of bays and estuaries along a
coastline can also magnify the intensity of
tides.
• Funnel-shaped bays greatly change tidal
magnitudes. When the tide is channelled
between islands or into bays and estuaries
they are called tidal currents eg: bay of
fundy, canada

34. Tides based on Frequency
1. Semi-diurnal tide
• The most common tidal pattern,
featuring two high tides and two low tides
each day
2. Diurnal tide
• There is only one high tide and one low tide
during each day.

35. 3. 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.

36. Tides based on the Sun, Moon and
the Earth Positions
1. Spring tides
• When the sun, the moon and the earth are in a
straight line, the height of the tide will be
higher.
• they occur twice a month, one on full moon
period and another during new moon period.

37. 2. 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.
• Like spring tides, these tides also
occur twice a month.

38. Imporatance of Tides
• Navigation- High tides help in navigation. They
raise the water level close to the shores. This
helps the ships to arrive at the harbour more
easily.
• Fishing
• The high tides also help in fishing. Many more
fish come closer to the shore during the high
tide
• Desilting
• Tidal power generation

39. • Consider the followings statements regarding
the spring tides:
• 1) During spring tide, the sun, the moon and the
earth are in a straight line.
• 2) The height of the tide will be higher during
spring tide.
• 3) Spring tides occur once a month.
• Which of the above statements is true?
• a. 1 and 2
b. 2 and 3
c. 1 and 3
d. 1, 2 and 3

40. Ans: A

41. • Q) What are tides? How are tides caused?
How are tides related to navigation?

42. Salinity of Ocean water
• Amount of salt found in 1000 gm of water
• Nacl (78%), MgCl2 (11%), MgSO4 (3.5%), CaSO4
(2.5%)
• Na and Cl has high residual time in ocean water –
very gradual removal – that’s why, they remain in
the highest proportion
• Standard salinity of ocean water is = 35.5 ppt –
salinity of Atlantic Ocean
• Dead Sea (350 salinity), Lake van (400), Lake
Urmia
• Man seldom drowned in sea with high salinity
• Because, high salinity = high density

43. Sources of salts in ocean water
• Sediments carried by rivers
• Submarine volcanism at MOR
• Erosion of oceanic rocks
• Evaporation increases salinity

44. Factors affecting
• Rate of evaporation
• Fresh water added by ppt,streams and ice bergs
• Degree of water mixing
• Wind
• Ocean currents

45. Patterns of salinity
• Salinity decreases from equator to poles
• But highest salinity is not at the equator = because
high rainfall, cloud cover
• Highest salinity is at tropics

46. climatology
• Study process & phenomenon of climate
• Climate is the statistics of weather over long
periods of time.(abt 25yrs) eg: monsoonal climate,
British climate
 Weather is the state of the atmosphere, describing
for example the degree to which it is hot or cold,
wet or dry, calm or stormy, clear or cloudy
 Parameters of weather-
temperature, humidity, atmospheric
pressure, wind, precipitation etc

47. Temperature
• basic parameter
• Avg global temp-15 deg
• highest temp-58c-Azizia ,libya sahara desert
• Lowest- minus 89.2c-antarctica
• Temp influenced by latitudes, duration of
sunshine,cloud cover,nature of earth surface( high-
barren rocks than water), albedo property( amt of
insolation reflected), altitude, distance from sea
directly proportional to temperature

48. humidity
• moisture content of atmosphere
• avg humidity- 0 to 5%
• Based on it-areas divided –arid , semi arid, humid and
per humid
• more humidity-more energy in atm-more disturbance
• precipitation occurs when humid air is condensed
• Relative humidity -ratio between moisture present to
moisture required- hygrometer- avg -35 to 40%

49. Atmospheric pressure
• weight exerted by column of atm air on unit of
surface of earth
• It is inversely proportional to height
• Measured by Barometer
• Factors which control atm pressure:
1. temperature-it directly proportional to pressure
2. Dynamic factors- when air moves up(assend) –
pressure decreases;when air decends-pressure
increases

50. Composition of
atmosphere
• Atmosphere is layer of gases surrounding
earth
• Homosphere –upto ionosphere-uniform gas
composition
• Heterosphere-above inosphere-non uniform
gas composition

51. Composition of atmosphere
Gas Proportion
Nitrogen 78%
Oxygen 21%
Argon 0.93%
Carbon dioxide 0.03%
Neon 0.0018%
Helium 0.00005%
ozone 0.00006%

52. Structure of atm

71. Pressure belts and trade winds
7 belts:
• equatorial low pressure
belt(ELP)
• sub-tropical high pressure
belt(STHP)-2
• sub-polar low pressure
belt(SPLP)-2
• Polar High pressure area
(PHP)-2

89. Jet streams
• Jet streams are relatively narrow bands of strong wind
in the upper levels of the atmosphere. The winds blow
from west to east in jet streams but the flow often
shifts to the north and south.
• Jet streams follow the boundaries between hot and
cold air.
• Jet streams are like rivers of wind high above in the
atmosphere. These slim strips of strong winds have a
huge influence on climate, as they can push air masses
around and affect weather patterns.

90. • Both the Northern and Southern
hemispheres have jet streams, although the
jet streams in the north are more forceful.
Each hemisphere has two primary jet
streams — a polar and a subtropical. The
polar jet streams form between the
latitudes of 50 and 60 degrees north and
south of the equator, and the subtropical
jet stream is closer to the equator and
takes shape at latitudes of 20 to 30
degrees.

92. Tropical cyclones
• Tropical cyclones is an atmospheric system of rapidly
circulating air mass about a low pressure center,
usually accompanied by storm often destructive
weather
• They are irregular wind movements involving closed
circulation of air around a low pressure center. This
closed air circulation (whirling motion) is a result
of rapid upward movement of hot air which is
subjected to Coriolis force. The low pressure at the
center is responsible for the wind speeds.
• The cyclonic wind movements are anti-clockwise in
the northern hemisphere and clockwise in the
southern hemisphere (This is due to Coriolis force).

93. Conditions Favourable for Tropical
Cyclone Formation
• Large sea surface with temperature higher
than 27° C,
• Presence of the Coriolis force enough to
create a cyclonic vortex,
• Small variations in the vertical wind speed,
• A pre-existing weak low-pressure area or low-
level-cyclonic circulation,
• Upper divergence above the sea level system,

94. Origin and Development of Tropical
Cyclones
• The tropical cyclones have a thermal origin, and they
develop over tropical seas during late summers (August
to mid-November).
• At these locations, the strong local convectional
currents acquire a whirling motion because of the
Coriolis force.
• After developing, these cyclones advance till they find
a weak spot in the trade wind belt.
• Under favorable conditions, multiple thunderstorms
originate over the oceans. These thunderstorms merge
and create an intense low pressure system (wind is
warm and lighter).

95. Structure of a tropical cyclone

96. • Eye
• The “eye” is a roughly circular area of
comparatively light winds and fair weather found at
the center of a severe tropical cyclone.
• There is little or no precipitation and sometimes
blue sky or stars can be seen.
• The eye is the region of lowest surface pressure and
warmest temperatures aloft
• Eye wall
• The eye is surrounded by the “eye wall”, the roughly
circular ring of deep convection, which is the area
of highest surface winds in the tropical cyclone. Eye
Wall region also sees the maximum sustained winds
i.e. fastest winds in a cyclone occur along the eye
wall region.
• The eye is composed of air that is slowly sinking and
the eye wall has a net upward flow

97. • Spiral bands
• Another feature of tropical cyclones that
probably plays a role in forming and
maintaining the eye is the eye wall
convection.
• Convection in tropical cyclones is organized
into long, narrow rain bands which are
oriented in the same direction as the
horizontal wind.
• Because these bands seem to spiral into the
center of a tropical cyclone, they are called
“spiral bands”.

98. Regional names for Tropical Cyclones
• Regions What they are called
• Indian Ocean Cyclones
• Atlantic Hurricanes
• W.Pacific &South China Sea Typhoons
• Western Australia Willy-willies
• USA tornadoes

99. Tornado
• From severe thunderstorms sometimes spiraling wind
descends like a trunk of an elephant with great force,
with very low pressure at the center, causing massive
destruction on its way. Such a phenomenon is called a
tornado.
• Tornadoes generally occur in middle latitudes.
Especially on land surface
• Tornado is a small-diameter column of violently
rotating air developed within a convective cloud and in
contact with the ground.
• It can last from few seconds to more than an hour.
• These whirling atmospheric vortices can generate the
strongest winds known on Earth: wind speeds in the
range of 500 km (300 miles) per hour.

100. Temperate cyclone
• Polar Front Theory
• According to this theory, the warm-humid air masses
from the tropics meet the dry-cold air masses from the
poles and thus a polar front is formed as a surface of
discontinuity.
• Such conditions occur over sub-tropical high, sub-
polar low pressure belts and along the Tropopause.
• The cold air pushes the warm air upwards from
underneath. Thus a void is created because of
lessening of pressure. The surrounding air rushed in to
occupy this void and coupled with the earth’s rotation,
a cyclone is formed which advances with the
westerlies (Jet Streams)

101. • Dynamic Origin – Coriolis Force, Movement of
air masses.
• Latitude-Confined to 350 – 650 N and S of
equator..
• The very cyclone formation is due to
frontogenesis
• Can form both on land as well as seas

102. Climatic regions of the world
 Equatorial region- low land and high land
 Tropical and sub tropical-eastern
margin,weastern margin and interior
 Warm temperate region-west, east,interior
 Cool temperate region-west,east,interior
 polar region-low land & high land

103. Equitorial region( 10N-10S)
• 1. low land-Amazon type- amzon basin
brazil, congo basin, indonesia,etc
• Climate- uniseasonal, hot and humid
throughout the year-21c
• avg rainfall – above 250cm- convective
rainfall
• double maxim PPT

104. • natural vegetation- evergreen forest-selvas-3 layered
• Largest biodiversity
• Breeding ground for poisonous mosquitoes, reptiles ,snakes
etc
• trees- ebony, rosewood, greenheart etc
• rich fauna-climbers, reptiles insects etc
2. Equitorial highlands- Equador type
Peruvian plateau,columbian plateau and equador
Climate- less rain( 120cm)- no convection currents
Vegetation- evergreen and semi-evergreen –no 3 layer
Upper reaches –grassland-support livestock

105. Tropocal and sub- tropical(10-30
latitude)
1. Eastern margin of continents
a. Monsoonal climate- india SE asia, philippines and N
australia
Climate-summer , and winters seasons
100-150 cm rain- summers are hot and humid- winters are dry
Seasonal reversal of winds
Vegetation- Monsoonal forest- tropical descidous-sal ,teak
,arjun etc- evergreen in some areas
Intensive agriculture

106. B. Modified mosoonal or caribean region- cental
america
Climate- summer and winter
Winters are not fully dry
rainfall -150cm
Semievergreen forest- no deciduous
2. Western margin of continents- sahara/ hot desert
West africa, mojave( usa), atakama( s.america)thar
desert, australian desert etc
Climate- 6 months summer, 6months winter
Highest temp- Azizia( libya)
Less rain- wind subsidence ,offshore winds and cold
cuurents
Vegetation-sparse-bushes and shrubs
Borrowing animals-rats rabits-

107. • Interiors of continents-( sudan type and savanna
type)
Sudan, malavi,kenya , brazilian plateau, cental australia
Climate-distinct summer and winter
Summers are hot and semi arid- rainfall- 50 to 60 cm
Winters are warm to cool and dry winters
Support grasses- tall and dense-elephanta grass
Richest wildlife- big game country

108. Warm temperate( 30 to 60)
1. Western warm temperate- mediterranean type-
california,central chile,southern aust
Climate- distinct summer and winter
Summers are warm and winters are cool and never
frozen
Rainfall- summers dry and winters humid( 70 -75cm)
Vegetation- mediterranean forest- semi or evergreen-
olive ,cork and fig
Orchards-cytrus fruits

109. 2. Eastern margin- china type-east usa,se aust,south japan
Climate-distinct summer and winter
Summers more hotter thn meditarranean- winters are cool
Rainfall is high-100cm-Summer rain – maritime favours
Vegetation-temperate broad leaved deciduous forest-
eucalyptus, magnolia
3. Interiors- lowland –Turanian/ steppe type
Central asia, siberia, great basin of usa, argentina and
uruguay
Climate -6-6
Summers are warm to cool – winters cool too cold and
frozen

110. • rainfall- moderate-40 to 50 cm
• Vegetation-temperate grassland-short and soft
• Support livestock
• Priaries- Usa, pampas- Argentina, Downs- Australia,High
velds- south africa
B. Highlands- Iranian type-iran and patagonian plateau of
chile- gobi desert
Climate-6-6
Summers similar to steppe
Winters- cold and frozen-snowfall
Vegetation- temperate bushes and shrubs

111. Cool temperate region ( 60-80)
• 1. western margin- British type-
• Western europe,NW usa,south chile, south
australia and newzealand
• Climate- 6-6
• Summers are cool, winters are cool to cold,
occasionally frozen
• Rain-100-200cm, winters r nt dry
• Vegetation-temperate forest- Oak,chestnut
mapple-broadleaved headwood
• Commercial dairy farming-dedicated pasture
land

112. 2. eastern margin- St lawrence type
• East canada, east china, Japan and korea
• Climate -6-6 summers cool and winters are
cold( more harsh)- rainfall high
• Vegetation-semi to evergreen-Oak, chestnut,
mapple

113. 3. Interior region- Siberian type/ taiga type
Siberia and north canada
Climate-6-6-summers cool to cold, winters cold to
frozen continentality –high thermal range( 80deg)
Low rainfall-50cm
Vegetation-coniferous trees-pine, fur, cedar-soft wood-
paper manufacture

114. Polar regions(80-90)
1. Low land- tundra type
Arctic region of continets
Climate- 3 months summers, 9months winter
Summers-cool, winters- frozen
Vegetation-bushes and grasses
2. High land- greenland variety
Greenland, Iceland and antarctica
No summer
Permafrost region
No life

115. The end