Know more about geography

1. Temperature
Temperature and its vertical distribution in
ocean water
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Uploaded by : Tanuj Pareek
College :- Kirorimal College
University of
Delhi
Student At KMC

2. Ocean Water
With respect to temperature, there are three layers in the oceans from surface to
bottom in tropics-
1. The first layer-
Top layer of warm oceanic water
500 m thick
Temperature – 20-250c
 present throughout the year in Tropics
Mid-latitudes – Only in summer
2. The Thermocline layer-
Vertical Zone of oceanic water below first layer or 500m
Rapid rate of decrease of temperature with increasing depth
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3. 3. The Third layer-
Very Cold (due to decreasing temperature)
Extends up to the deep ocean floor from Thermocline layer
Polar areas have only one layer of cold water
Where change in temperature become more or less Nil
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4. Daily and annual range of temperature
1. DROT –The difference of maximum and minimum temperature of a day(24 hours)
is known as Daily range of temperature.
The DROT of surface of water of oceans is almost insignificant as it is 10C.
 DROT at –
1. low latitudes – 0.30C
2. High latitudes - 0.20C to 0.30C
+ The heating and cooling of ocean water is rapid under clear sky and vice versa.
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5. 2. AROT – The difference between maximum and
minimum temperature of a year called as Annual
range of temperature are recorded in August and
February (in northern hemisphere) respectively.
Usually, The AROT of ocean water is -120C
 The AROT is higher in the enclosed seas
than in the open sea
For example – Baltic sea records AROT 4.40C
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6. Factors affecting Distribution of temperature(Ocean)
Distributional pattern of temperature of ocean water is studied in two ways –
(i) Horizontal distribution (temperature of surface water)
AND
(ii) Vertical distribution (Surface water to the bottom)
Factors are :
1. Latitudes
2. Unequal distribution of land and water
3. Prevailing wind
4. Ocean currents
5. Other minor factors
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7. Vertical distribution of Temperature in oceanic water
Introduction
Maximum temperature of the oceans is always at their surface
because it receives the insolation and the heat is transmitted to
lower sections of the oceans through mechanism of conduction.
The solar rays very effectively penetrate up to 20m depth and
they hardly go beyond 200m depth.
Consequently, the temperature decreases from the ocean
surface with increasing depth but the rate of decrease of
temperature with increasing depth is not uniform everywhere.
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8. Oceans are divided into two zones.
(1) Photic or euphotic zone :-
– Represents the upper surface up to the depth of 200m
– Receives solar radiation
(2) Aphotic zone :-
– Extends from 200m depth to the bottom
– Doesn’t receive solar rays
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9. Salient features of vertical distribution of temperature(Ocean):
• Sea temperature decreases with increasing depth but the rate of decrease of
temperature is not uniform.
• Below 2000m change in sea temperature is negligible.
• The rate of decrease of temperature with increasing depth from equator towards
the poles is not uniform. Though the surface temperature decreases from
equator towards pole but at the ocean bottoms is uniform from equator towards
poles.
• The areas from where sea surface water is driven away offshore winds resulting
into upwelling of water from below record low temperature at sea surface and
thus the rate of decrease of temperature with increasing depth becomes low and
Contrary to this the sea water because of onshore winds, record relatively high
temperature at sea surface and thus the rate of decrease of temperature with
increasing depth becomes rapid.
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10. Clear cut division of ocean water
• HOW?
There is clear cut thermal structure of ocean water.
Vertically the oceans are divided into 3 layers (Thermal): -
(1)Upper layer –
 represents top layer of warm water mass
 Average temperature – 200C to 250C
Lighter oceans water mass floats over thickest heavy water
mass
Present at – tropics – throughout the year
- mid latitudes – only in summers
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11. (2) The lower layer –
Extends beyond 1000m depth up to the ocean bottom Very Cold
Represents denser water mass
(3) The Thermocline layer –
Thermo – temperature ; Cline – Change
The upper and lower water masses are
separated by a transitional zone of rapid
change of temperature with increasing
depth. This zone is called as
Thermocline.
Extends between 300m-1000m depth
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Graph showing a
tropical ocean
thermocline (depth vs.
temperature). Note the
rapid change between
100 and 1000 meters.
The temperature is
nearly constant after
1500 meters depth.

13. Diurnal and seasonal thermoclines
• Seasonal thermoclines –
1. between 40 m to 100 m
2. Formed due to heating of water surface through solar
radiation during summer seasons
• Diurnal thermoclines –
1. Form in shallow water depth usually less than 10-15m
2. The polar seas have only one layer of cold water mass
from top to bottom in ocean
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Seasonal
thermocline
and
Permanent
thermocline

15. Feedback
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