This PPT slide gives information on monsoon and drought climatic conditions

2. Introduction
• “Water is life” a famous quote.
• Many suktas to be found in the Vedas
and Upanishads about water.
• The first traces of human civilization and
settlements were witnessed by rivers.
• Water has played an important role in the
development of human race.
• Water in science is H2O

3. Rains
• Various sources of water.
• the purest and important source is rain.
• Rain is a blessing that connects heaven
and earth.
• The water cycle is one of the most
important cycles of nature.

4. The hydraulic cycle
• The water cycle is the way the Earth uses and recycles
water. It's controlled by the sun, which produces
energy in the form of heat. This heat energy causes
the water in the world's oceans, lakes, and even
puddles in your backyard to warm and evaporate.
• When water is heated, it changes from a liquid to a
gas. This gas is called water vapor, and the process is
called evaporation. When plants give off water vapor,
it's called transpiration.

5. • When water evaporates, it rises into the cooler
air, collects, and forms clouds. There, the water
vapor molecules cool down and change back
into liquid water. This is called condensation.
• As more and more water vapor cools into the
clouds, the water droplets that form the clouds
become larger and larger. These droplets get so
big that the swirling winds in the atmosphere can
no longer hold them up. The droplets fall from
the sky.
• Precipitation is the term for the falling,
condensed water molecules, which come down
as rain, snow, sleet, or hail--depending on
conditions in the atmosphere.
..

7. When water falls to the Earth, the water seeps into the soil
because of the force of gravity. This seeping is called
infiltration. Or the water flows over the land and into bodies of
water, such as rivers and lakes. Sometimes this water
collects nutrients from the soil it runs over, making the valley
good for plant growth.

8. Monsoon
• Comes from an Arabic word “mausim”.
Means season.
• The ancient traders traveling in the Indian
ocean and Arabian sea used this term to
describe the system of alternating winds
which blew from northeast during winter
and southwest during summer.

9. Definition
• Monsoons are seasonal rains that
drench the countryside with water.
• They are annually recurring weather
phenomenon.

10. Reasons for monsoon
• Due to land and sea temperature differences.
• land reflects the sun’s rays heating air over
land more rapidly. The specific heating capacity
of components of earth is much more than
water.
• water is able to absorb a lot of heat without
itself changing temperature much. So air over
water remains relatively cooler. This creates
high and low pressure areas.

11. Differential heating phenomenon

12. • the air over high pressure areas migrate
to low pressure areas. As the heated air in
low pressure area rises up, the air from
high pressure areas takes its place.
• The winds that blow from sea to land carry
humidity and as they move towards low
pressure areas i.e. land, they rise up due
to mountains, surface heating,
convergence at the land. Thus the air
cools due to expansion in lower pressure
causing condensation.

13. • This cycle continues as cooling air creates
precipitation and releases energy. this energy
heats the air which rises and flows back to the
sea. cools and rushes back to the land to
replace more warm air.
• This phenomenon is observed in Asia as the
northern hemisphere has much more land
mass than southern hemisphere.
• during summer the earth is tilted at such an
angle that the sun’s rays shine more directly on
the northern hemisphere heating the land
mass.
• thus it is a cyclical process.

14. Seasonal wind currents

15. Types of monsoon.
• In the Indian subcontinent 2 types are
observed.

16. Southwest or summer monsoon.
• Occurs during summer. in the northern
hemisphere low pressure area is created.
winds from southern hemisphere blow north
to replace the hot winds. These carry
moisture. thus winds blow from Indian ocean
towards central India.
• From June to September.

18. • Northeast or winter monsoon.
• occurs during winter. the sea water holds
heat whereas the land cools off
immediately. Thus low pressure is created
over the ocean. Cold winds blow from the
land to the sea collecting moisture from
tropical waters as they travel and release
it over Indonesia,Srilanka, Indian east
coast.
• from December to early march.
• Also known as the retreating monsoon.

20. History
• Asian monsoon is linked to the upliftment of
Tibetan plateau after the collision of India and
Asia around 50 million years ago.
• monsoon first became strong around 8 million
years ago. Based on records from the Arabian
sea and the records of wind blown to the loess
plateau of china.
• varied significantly in strength since then. linked
largely to global climate change.
• Strengthening of Indian monsoon happened
around 5 million years ago due to an interval of
closing of Indonesian seaway. This increased
sea surface temperature.

21. • Thus today monsoon is an important
feature of the Indian sub continent.
• it is the biggest support to the agriculture
here and even other related industries.
• Along with the Indian subcontinent, and
other parts of Asia monsoons also occur
in north America, Africa, south America.

22. Measurement
• Rain is generally
measured in millimeter
i.e. mm. this shows the
quantity of rainfall over
a particular area. It can
also be converted to
cm. or meters.
» simple rain gauge -

23. Meteorological dept.
• This department deals with the
temperature, weather of an area. It
predicts the weather and thus gives alert
signals in case a natural calamity
predicted to occur.
• gives us the daily report of how much
rainfall occurred in which area and also
what will be the situation in the next 48
hours. It also predicts when monsoons will
hit which region and so on.

24. Satellite images
• provides us with
the satellite images
which enable us to
know where the
clouds are heading
and regions which
will get heavy
rainfall.

26. Monsoons in India

27. Droughts
• When there is not enough rain to support
people or crops.
• It may rain but scanty rainfall.

28. Causes of droughts
• If no low pressure area is created then the
air currents and clouds are pushed
downwards .
• High pressure systems can be stalled by
jet streams, wide bands of fast moving air.
in the upper atmosphere.
• unusual currents of cold and warm water
in the ocean.
• Water vapor not brought by air currents to
the right area at the right time. if winds are
not strong.

29. Global wind currents

30. Causes of droughts
• Mountains can prevent winds from blowing
moisture to the needed areas. Such areas
are also known as rain shadow areas and
are generally drought prone. As the air
rises above a mountain it becomes cooler
and condenses. Thus deserts are found
on a side of a mountain facing away from
the sea.

32. Prediction
• Can know when occurred in the past by the
tree rings. wide rings show good growth and
thin rings means stunted growth.
• generally occur in the cycle of 22 years.
• Predicted that such patterns are caused by
sun spots i.e. dark cool areas on the surface
of the sun.

33. • These may cause slight
variations in air temperature
enough to cause a drought.
• But still not proved.

34. Preparation
• Need to limit the use
of water by each
individual.
• If situation is very
serious then need for
rationing of water

35. Year 2008
• This year the monsoons
arrived on time much to
everyone's surprise.
• Hit the coast of kerela on
25th
may and reached
maharashtra by 10th
June.
• At this time it was predicted
that like the 2 previous
years this year too there
will be good rainfall.
• the conditions were
favorable. low pressure
area created on the west
coast. Cyclones were
predicted in the bay of
Bengal.
• the north east region was
under low pressure areas.

36. Onset and retreat of monsoon in
India

37. Clouds over mumbai

38. • In maharashtra it rained for a week or so. Not
too heavily though. then it stopped raining on
around 15 June.
• The next predictions made were all very positive.
Low pressure areas had developed in the bay of
Bengal and also the central India.
• the satellite images showed clouds aligned on
the western coast. Headlines said 22nd
June.
• But days past by without the trace of rain.
Farmers had not sowed seeds. Others had but
they did not grow well as there was no rain.
• 2nd
July and pune had got around 19.9mm rainfall
• Meteorological dept. declared that the speed of
the winds this year was thrice than what it was

39. last year at the same time. last year the speed
was 4 to 12km per hr. whereas this year it was14
to 21km per hr.
• This led to decrease in air humidity. It was 52 to
68 in comparison to 70 to 90.
• The rate of evaporation from soil was more than
14 to16mm compared to 3 to4 mm last year.
• Due to the strong winds, monsoon did not
stabilize in maharashtra.
• They were blown towards Bengal, orissa,U.P.,
and the northeast
• Drought was declared in the state on 10th
July.
• People seen performing poojas and sacrifices to
rain god.

40. Wind speed

41. • The rains did not even reach 15% of the average
of last year’s rain during this time.
• Pune expected an average of 600 to 800 mm.
• Discussions about “prakalp varsha”. But no
decisions taken. it was declared to be too late.
this project was to create artificial rainfall by
spraying silver iodide on the gathered clouds
with the help of airplane. this makes the cloud
heavy and it bursts and precipitates.
• In the first week of august it started raining again
and on 5th
august vidarbha and konkan flooded
due to too much rain.
• Pune received around 6 mm rainfall in two days
from 3rd to 5th
.on 8th
it was 32mm.

44. Calculation of rainfall.
• Let us calculate the amount of water we receive
here in vigyan ashram.
• The average rainfall here is around 550mm.[ the
calculated from the rainfall of last 10years.]
• The area in consideration is 5 acres. that
compromises of the ashram area. as per the
calculations, 1 acre=40 guntha. Thus the total
land is 200 gunthas.
• The area of one guntha is 10m *10m.

45. • The total area is thus 200* 100= 20000m2.
• The total requirement of the ashram if we
consider 50lt per person per day = 2000lt.
• since we have around 10 animals who need
about 60lt per day per animal = 600lt.
Therefore the total amount is 2600lt Per day.
• Thus the whole year’s requirement is 9,49,000
lit/year.
• The average rainfall is 550mm = 0.55m.
• Thus the total rainfall over this land = area*ht.
• =20000*0.55 = 11,000m3.
• One meter3 = 1000lt.
• Thus total amount in liters = 1,10,00,000 lt.

46. • If we save even 10% of this it means we
get 11,00,000 lit which is 1,51,000 lt.
more than what we need.
• Taking the lowest rainfall i.e. 250mm we
still get 50,00,000 lt and 10% of this
means 5,00,000 lt.

47. • So is it that nature provides us with less
rain or is it that we do not value the gift?
• it is time to ask our selves and stop
blaming nature.
• Droughts may not always be natural
calamities but in fact are many times
political.
• what we can do is harvest every drop of
water …….