OCEANS:SALINITY,TEMEPRATURE,WAVES,TIDES,OCEAN CURRENTS,RELIEF OF OCEAN FLOOR ETC.

1. OCEANS-TEMPERATURE

2. INTRODUCTION
• Oceanography is the branch of Physical Geography which studies about
the distribution of oceans in world.
• 71% of earth surface is covered by water and 29% is by land.
• As a maximum of earth surface is covered by water, it is called a Blue
Planet.
• Distribution of oceans is more in southern hemisphere as maximum
portion of northern hemisphere by land.
• There are five oceans i.e. Pacific Ocean, Atlantic Ocean, Indian ocean,
Arctic Ocean and Antarctica. The largest ocean among all this Pacific
Ocean.

3. Hydrological Cycle
• Water moves in a continuous cycle and changes from one form to
another.
• Water from the surface of earth evaporates on heating ad changes
from liquid to gas. This process of change of water vapour from
liquid to gas is called evaporation.
• Water vapour is carried by the air to a particular height where
condensation of water vapour takes place and result in forming
clouds. This process of change of water vapour from gas to solid is
called Condensation.
• When the cloud is not able to hold the condensed water vapours,
they fall on the surface of Earth in form of rain, snow etc. This
process of falling of water vapour on surface of earth in form of
rain or snow is called precipitation.
• This continuous interchange of forms of water on surface of earth
is called Hydrological Cycle.

5. Temperature of Ocean water
• Ocean water temperature increases when it receives
insolation from sun. Temperature of ocean water is not same
rather it varies from place to place and time to time.
• Various factors affecting ocean water temperature are:
• 1. Latitude: temperature of ocean water is more near to
equator and less at poles. It is because of more heat
received by the sun near equator as compared to poles.

6. • 2.Winds: In difference in temperature and pressure
conditions result in movement of wind from one area to
another. Warm winds increases the temperature of the region
it passes and and cold wind decreases the temperature of the
region it passes.
• 3.Ocean currrent: Movement of water by wind in a particular
direction is called ocean current. Warm ocean current
increases the temperature of the region it passes like Gulf
Stream and Cold current like Labrador current near Greenland
decreases the temperature of the region it passes.

7. • 4. Unequal distribution of Land and Sea:
• Distribution of land is more in northern hemisphere
as compared to southern hemisphere. Therefore
oceans in the northern hemisphere like Pacific
Ocean are warmer as compared to oceans in
southern hemisphere like Antarctica.

8. • 5.Icebergs: Icebergs decrease the temperature
of the ocean water of which they are present.
• 6.Salinity: Oceans with high salinity like
tropical areas have more temperature as
compared to oceans near poles like Arctic
Ocean.

9. Vertical Distribution of Temperature I
Oceans
• Temperature of oceans is
maximum at surface because of
heat received by the sun. As we
go down the ocean surface,
temperature starts decreasing.
• The region from where there is
certain decrease in temperature
is called Thermocline.
• 90% of total volume of water is
present below thermocline.

10. • The first layer of Thermocline
ranges between 0-500 metres
with temperature ranging
between 20-25°C. it is present
near tropical areas.
• The second layer of Thermocline
ranges between 500-1000
metres with temperature ranging
between 8-16°C. it is present
near temperate areas.
• The third layer of Thermocline is
very cold and extends upto the
depth of ocean floor.the
temperature ranges between 0-
4°C. it is present near polar
areas.

11. Horizontal Distribution of Temperature
in Oceans.
• Horizontal Distribution of temperature in oceans is
studied with the help of distribution of land and sea.
• In northern hemisphere distribution of land is more as
compared to southern hemisphere.
• Oceans in northern hemisphere have a higher
temperature like Pacific Ocean as compared to Southern
hemipshere like Antartica.
• Temperature in oceans of tropical zone is 27°C, 14°c in
temperate lattitudes and 0°c near poles.
• The rate of decrease of temperature is 0.5°c per lattitude
in oceans.
• The average temperature for all oceans is 17.2°C.

13. OCEANS-SALINITY

14. Introduction
• Salinity refers to presence of
dissolved salts in sea water.
• It is calculated as ppt or parts
per thousand grams of sea
water.
• The average salinity of sea
water is 35 per thousand
grams of sea water.
• Salts Ppt
Chlorine (Cl2) 19
Sodium(Na) 10
Sulphate(SO4) 3

15. Factors Affecting Salinity
• 1.Temperature: Areas which are
near to equator have high
temperature which result in high
evaporation and adding salts on
ocean surface.
• 2. Fresh Water: Areas which
receive fresh water from rivers
have low salinity. Fresh water mixes
with the water with salts and thus
reduces its salinity.
• 3. Ocean Currents: Warm Ocean
currents carry high saline water to
the area they move and cold
currents carry less saline water to
area they move.

16. HORIZONTAL DISTRIBUTION OF
SALINITY
• 1. Salinity in Open Seas:
• Open seas are the seas which have access to fresh water.
If open seas are located near to Equator they will have
less salinity because heavy rainfall will increase the fresh
water and decrease the salinity.
• Salinity is also less in polar areas because melting of ice
adds fresh water and help in decreasing the salinity.

17. • 2 Salinity in partially enclosed seas:
• Partially enclosed seas are the seas which are
partially covered by land and other by sea like
Mediterranean Sea, Red sea and Baltic Sea.
• Mediterranean Sea have high salinity because
of its location in high temperature area which
increases the evaporation rate and absence of
large rivers helps in increasing the salinity in
the area.

18. • Salinity of Enclosed Seas:
• Enclosed seas are the seas which are covered
from all sides.
• Lake Van in Turkey have 330 ppt as the salinity,
Dead Sea have 24 pt salinity and Great Salt
Lake have 220 ppt salinity.

19. Vertical Distribution of Salinity
• On the sea surface salinity is increased by high
evaporation and is reduced by the addition of
fresh water.
• More salinity will add more salts to water,
make water more dense. With the increasing
depth the salts keep on depositing and salinity
increases with increasing depth.
• Halocline is the line which help in reflecting
the amount of salinity in the area.

20. Relief of Ocean Floor
or
Features of Ocean Floor

21. Introduction
• The ocean floor is not plain as believed.
• Floor of various oceans have complex mountain ranges,
trenches etc.
• Tectonic plates movement, volcanic erruptions inside
oceans, depositional or erosion of material by sea waves
has resulted in its formation.
• The various features of ocean floor are:
• 1. Continental Shelf
• 2.Continetal Slope
• 3.Oceanic Deeps or Trenches
• 4.Abyssal Plains
• 5. Submarine Ridges
• 6.Abyssal Hills

23. • 1.Continental Shelf:
• It is the gentle seaward sloping surface extending
from coast towards open sea.
• It is formed by sediments brought down by rivers,
wind, waves etc.
• It covers 7.5% of total area of worlds ocean.
• It have a gentle slope 1°C and depth is normally
200 mts.

24. • Importance of Continental Shelf:
• Sun’s rays can’t penetrate upto Continental Shelf
which encourages growth and reproduction of
marine organisms.
• Marine food comes from this part of ocean floor.
• Provides richest fishing grounds.
• Storehouse of various minerals like petroleum and
natural gas.
• It is also storehouse of sand , gravel etc.

25. • 2.Continental Slope:
• It is the steep slope separating a continental
shelf and a deep ocean basin.
• The gradient of slope varies between 2-5°
• The depth of the slope is between 200-3600
mts.

26. • 3.Oceanic Deeps or Trenches
• These are deepest part of the oceans.
• They occur at the base of continental slope.
• They are long, narrow and deep in nature.
• They extend upto 5500 mts
• They are formed by the folding and faulting of the Earth’s
Crust.
• Mariana trench is the deepest trench of the Pacific Ocean.

27. • 4. Abyssal Plains
• These are also called as Deep Sea Plains.
• They are flat and smooth in nature.
• These plains are covered with fine sediments like
clay, silt etc.
• They are cover 40% of the ocean floor.
• they depth vary between 3000-6000 mts
• They are present in all major oceans and seas in
world.

28. • 5.Submarine Ridges:.
• It consist of various underwater mountain ranges
in sea.
• It is spread over thousand kilometers longs
• It is formed by converging or diverging of the
plates.
• They form the longest mountain system under
the Earth.
• Mid Atlantic ridge in Atlantic Ocean is the
example of Submarine Ridge.

30. • 6.Abbysal Hills:
• There are thousand hills inside the ocean floor. Various
hills are Sea Mount and Guyots.
• A)Sea Mount:
• It is the mountain peak which is rising from the ocean
floor but they are not reaching the ocean surface.
• They are of volcanic origin.
• They can be 3000mts to 4500 mts.
• Example Hawaiian Islands in Pacific Ocean in Japan

31. • B)Guyots:
• The flat bottomed sea mount is called Guyot.
• It is volcanic origin.
• Erosion of sea mount by various agents like
water, waves give this feature.
• Example: Hawaiian Sea Guyot in Japan.

33. OCEAN -WAVES

34. Introduction
• Ocean water is never static but keeps on moving
horizontally or vertically. The horizontal motion
refers to ocean waves and currents and vertical
motion is called tides.

35. OCEAN WAVES
• The movement of water due to energy produced by
wind is called Wave.
• A thing is floating up and down but it is carried by
the wind in a particular direction.
• As wave approaches the beach, it slows down. This
is due to friction between water and surface.

36. • The size of waves depend upon following factors:
• 1. Velocity of Wind: More the velocity of wind,
more will high will be the wave.
• 2.Duration of Wind: if wind moves a longer
duration of time, more waves will be formed.
• 3.Distance (Area) over which wave is moving:
• If wave is moving over an area with more speed,
long time, and over an area which does not stops it
then more high wave will be formed.

37. Terms associated with Waves:
• Crest: The upper part of the wave
is called Crest.
• Trough: the lower part of the wave
is called trough.
• Wavelength: The distance
between Crest and Trough is called
Wavelength.
• Waveheight: vertical distance
between Crest and Trough is
called Wave height
• Wave amplitude: Half of the wave
height is called Wave amplitude.
• Wave frequency: the number of
waves passing a given point during
one second time interval is called
wave frequency.

38. OCEAN -TIDES

39. OCEAN-TIDES
• The periodic rise and fall of sea level due to
gravitational attraction of sun and moon acting on
Earth is called tides.
• It occurs twice a day after 12 hours 26 minutes.
• The rise of sea level is called high tide or flood tide
and fall is called low tide or ebb tide.

40. ORIGIN OF TIDES
• 1.Gravitational pull of Sun and Moon
• Water of Earth is held in position by its own gravity but
gravitational pull of moon and sun acts on it.
• Due to large size of the sun, sun is attracting more but at large
distance it is not able to have more gravitational force.
• Moon’s size is low but its near to Earth so gravitational pull is
more

41. • 2. Centrifugal Force: It is force applied moving in
circular orbit. It moves from centre to outside.
• 3. Tide Generating Force:
• Difference between centrifugal and gravitational
pull of moon.

42. Types of Tides
• 1.On basis of frequency:
• 1.Semi-diurnal Tide: When there are two high and
two low tides in a day. But tides are of same height.
• 2.Diurnal Tide: There is one high tide and low tide
but the tides are of same height.
• 3. Mixed Tide: Tide having variations in high and
low tide is called Mixed tide.

43. • 2. On basis of Position of Earth, Moon and Sun.
• 1. Spring Tide:
• When Sun, Moon and Earth are in straight line,
they exert combined gravitational pull on Earth.
Therefore on both days tides are high.

44. • 2. Neap Tide:
• When Sun, Moon, Earth are at right angle it is
called Neap tide.
• Attraction of Sun and Moon tide to balance each
other as a result of which low tide is formed.

45. • When moon orbit is near to Earth it is called
Perigee and when moon is farthest from Earth
it is called Apogee.

46. Importance of Tides
• 1.Tidal force can be used for generating
electricity. Example in India, Gujarat Gulf of
Kuchch and Khambat have high potential.
• 2. Tides keep sea water in motion and avoids its
freezing.
• 3.tides leave shells and other sea products on
shore.
• 4. Fishermen go to open sea for catching fish on
high tide and come back on low tide.
• 5. Tides help in making river water navigable.

47. OCEAN CURRENTS

48. Meaning of Ocean Currents
• Regular movement of water in a particular
direction is called ocean currents.

49. Factors responsible for origin of
currents:
• 1. Temperature difference: At the Equator,
temperature is high and the water also becomes
light on heating. At the poles, the temperature is
low and water becomes dense. Difference in
temperature is also one the cause of movement
of water from polar areas to equator.
• 2. Prevailing Winds: Winds move in area due to
indifference in temperature conditions. When
winds blow in a particular direction and take the
water along is called ocean currents.

50. • 3.Evaporation: More evaporation reduces the level
of water and water moves from surrounding area to
balance the level of water.
• 4. Rotation of Earth: Due to rotation of Earth,
coriolis force becomes active because of which
winds move right in northern hemisphere and left
in southern hemisphere. Winds carry the water also
in its direction and give birth to currents.
• 5.Salinity differences: Water having high salinity is
denser and thus moves down. Light water with less
salinity moves toward it and a current is formed.
Example : Mediterrenean Sea have highest salinity
which thus causes to water move from Atlantic
Ocean.

52. TYPES OF OCEAN CURRENTS
• 1.ON THE BASIS OF DEPTH
• 1.SURFACE CURRENTS: The currents which are
prevalent over the surface of water. They
constitute over 10% of all water in the ocean.
• 2.DEEP WATER CURRENTS:
• When the water is carried by wind due to various
differences like salinity, density deep in the
oceans is called DEEP WATER CURRENTS. They
constitute 90% of total ocean water.

53. • 2. ON THE BASIS OF TEMPERATURE
• 1.WARM CURRENTS:
• The currents which move from warm areas of
tropics to cold areas of polar latitudes is called
warm currents. They increase the temperature of
the area to which they go. Example: Gulf Stream is
a warm current in Atlantic Ocean.
• 2. COLD CURRENTS:
• The currents which move from cold areas to warm
areas is called Cold Currents. There temperature is
lower so they decrease the temperature of the
area they go. Example: Canaries current is a cold
current.