science 8

1. TYPHOON
Causes and mechanisms,
impacts and effects, and
Mitigation

2. What is Typhoon?
• Tropical Cyclones that develops in the north-
western part of the Pacific Ocean
between 180° and 100°E.
• In the Philippines, tropical cyclones (typhoons) are
called bagyo. The term bagyo, a Filipino word
meaning typhoon arose after a 1911 storm in the
city of Baguio had a record rainfall of 46 inches
within a 24-hour period..

3. Typhoons are categorized into five:
• Category 1 - Tropical Depression
-sustains winds between 119 and 153 km/hour (km/h).
It is the first notable stage in the formation of a hurricane.
(Morakot)
• Category 2 - Tropical Storm (TS)
- has winds between 154 and 177 km/h.
-a tropical storm is a system of intense thunderstorms
that progressively intensifies.
• Category 3 - Strong Typhoon
-A strong typhoon is a system of low pressure and
intense winds (between 178 and 209 km/h).(Maemi-South
Korea)

4. • Category 4 - Intense Typhoon (or Hurricane)
-An intense typhoon sustains high winds of 210
to 249 km/h and is classified as a category-5 storm,
which carries the highest element of risk.
• Category 5 - Violent Typhoon
-A violent typhoon is characterized by winds
exceeding 249 km/h.

5. • Variability in Activity
On an annual time scale, activity reaches
a minimum in February, before increasing
steadily through June, and spiking from
July through October, with September
being the most active month for tropical
cyclones in the Philippines. Activity falls
off significantly in November.

6. List of Philippine Typhoon
(1970-2011)
Name Period of
occurrence
Deaths Damage
(in billion)
Highest wind
speed in kph
Areas most
affected
Sening
(Joan)
October
11-15,1970
768 10.7 280 Bicol
region,calabarzon
Herming
(betty)
August o7-
14, 1987
94 39.9 260 Samar, Bicol
Region
Ruping
(Mike)
November
10-14,
1990
748 18.2 285 Cebu C
Harurot
(Imbudo)
July 13-
24,2003
64 3.87 240 Cagayan
Valley,CARIlocos
region
Unding
(Muifa)
November
14-26,2004
69 3.87 240 Bicol Region,
MIMAROPA

7. • Milenyo (Xangsane)-2006
• Frank (Fengshen) – 2008
• Ondoy (Ketsana) – 2009
• Bebeng (Aere) – 2011
• Ambo (Mawar) – 2012

8. These are the ff. typhoons hits in the Philippines
(2012)
• AMBO
• BUTCHOY
• COSME
• DINDO
• ENTENG
• FRANK
• GENER
• HELEN
• IGME
• SIONY
• TONYO
• YOYONG
• ZOSIMO
• JULIAN
• KAREN
• LAWIN
• MARCE
• NINA
• OFEL
• PABLO
• QUINTA
• ROLLY
• ULYSSES
• VICKY
• WARREN

9. CAUSES OF TYPHOON
TRANSFORMATION
Pre-conditions and Conditions
of Typhoons

10. PRE-CONDITIONS OF
TYPHOON FORMATION
MONSOON TROUGH
This is an extension of the
Inter- Tropical
Convergence Zone where
cyclonic spin has
developed. The ITCZ is a
trough is a low pressure
created by the
convergence of the
northeast and southeast
trade winds.

11. TROPICAL UPPER
TROPOSPHERIC
TROUGH
The typical low
pressure center that
forms a typhoon
starts at the lower
levels and is warm
compared to its
environment.

12. FRONT
Stall over tropical
water.
A front has a cyclonic
spin associated with
it. If winds aloft
become favorable
with little wind shear,
showers and storms
could become more
numerous and cause a
typhoon to form.

13. MESOSCALE
CONVECTIVE
SYSTEM
These organized
clusters of storms can
move off a continental
landmass and drift
over warm waters. If
they already contain a
small vortex in the
cluster, this may make
to region even more
favorable for tropical
cyclone development.

15. 7 BASINS WHERE TROPICAL CYCLONE DEVELOPS
• NORTH ATLANTIC OCEAN
June 1- November 30. The
most active period runs
from about mid August
through the latter part of
October.
( Caribbean, Bermuda, Central
America etc.)
• EASTERN NORTH PACIFIC
OCEAN
May 15 - November 30.
This is the second most
active region for tropical
cyclones in the world.
These storms mostly move
into the open eastern
Pacific Ocean but can
affect western Mexico and
sometimes after
developing, Hawaii.

16. • ARABIAN SEA ( Severe
Cyclonic Storm)
April 1 - December 30. This
basin has a double
maximum because of the
monsoon trough moving
through at two different
times of the year.
• SOUTHWEST PACIFIC
OCEAN (STC)
October 15 - May 1. These
tropical cyclones may affect
eastern Australia.
• NORTHWEST PACIFIC
OCEAN(Typhoon)
All year. This is the most
active basin in the world.
Most typhoons form
between July through
November. The tropical
cyclones that form here
can affect the Philippines,
Southeast Asia including
China and Taiwan, and
Japan.

17. • SOUTHEAST INDEAN
OCEAN ( STC)
October 15 - May. These
tropical cyclones may affect
northern and western
Australia. This basin has a
double maximum in mid
January, and mid February
through early March.
• SOUTHWEST INDIAN
OCEAN ( TC)
October 15 - May 15.
These tropical cyclones
may affect Madagascar
and south-eastern Africa. A
double maximum occurs in
mid January and mid
February through early
March.

18. THE LIFE OF A TYPHOON
THE FOUR STAGES OF THE LIFE OF A
TYPHOON

19. •FORMATIVE STAGE
•IMMATURE STAGE
•MATURE STAGE
•DECAYING STAGE

21. EFFECTS OF TYPHOON

22. BUILDINGS AND INFRASTRUCTURE
The two most destructive forces
associated with typhoons are
wind and rain. According to the
Green Fun website, typhoon
winds can affect buildings and
other structures in two ways:
through direct force and through
projectiles. The heavy and
persistent rainfall that typhoons
bring can also have devastating
effects. In addition to making
homes uninhabitable, the flooding
associated with typhoons can
make roads impassable, which can
cripple rescue and aid efforts.

23. TREES AND VEGETATION

24. WATERCRAFT AND WATER OPERATIONS

25. L
I
F
E

26. ECONOMICAL EFFECTS
• Different countries experience different types of natural
calamities. US are known for experiencing devastating
hurricanes while Japan is prone to earthquakes and
tsunamis. The Philippines, on the other hand, has had its
fair share of typhoons and tropical storms. Aside from
Ondoy, our country has experienced several devastating
typhoons. In the table below, we summarize some of the
most financially-damaging typhoons that our country has
dealt with

27. EFFECT ON THE STOCK MARKET
• Aside from the economic effects of typhoons and
floods, we also want to show the effect of natural
disasters on the stock market. A few days after
typhoons Milenyo and Ondoy, the PSE Index was
slightly down compared to where it was before the
typhoons occurred. Similarly, the PSE Index is down
0.4 percent, on lethargic trading, three days after
the peak of the recent rains and floods.

28. IMPACTS
• Natural disasters can have important
implications for public finance.
Disasters are likely to result in
additional expenditure and/or the
partial reallocation of already
committed financial resources, with
implications for planned investment
and other expenditures. Public
revenue may also decline as levels of
economic activity fall. In consequence,
a government may face increasing
budgetary pressures which could in
turn increase levels of domestic
and/or external borrowing or
increasing the money supply, each, in
turn, with potentially significant
knock-on effects (Benson and Clay,
2003).
FISCAL IMPACTS

29. M
I
T
I
G
A
T
I
O
N

30. • Know your enemy: hazards
and their effects
• Identifying which these are–
the elements most at risk–
indicates priorities for
mitigation.
• Vulnerability
• Tools, powers and budgets.
• PRECAUTIONARY
MEASURES
• Natural Disaster Reduction
Assessment
• POLICIES
• Suspension of Classes,
Work and Activities during
Typhoons
• DepEd Order No. 28 series of
2005: GUIDELINES ON THE
SUSPENSION OF CLASSES
WHEN TYPHOONS AND OTHER
CALAMITIES OCCUR.
• DEPED Order No. 50 s. 2007
with NDCC Memorandum No.7
s. 2006.
• Philippine Storm SIGNAL
WARNINGS (PSWS)

31. CONCLUSION/RECOMMENDATION
• Natural disasters, both natural and manmade, can and will occur,
often with little or no warning. It has tremendous effect not only
physically but also on the mental aspect of an individual especially
the younger ones. Disasters often strike without warning and
cause damages that limit or prevent an adequate response. We
have to commit ourselves to understanding these hazards and to
applying techniques that reduce our vulnerability. We need to
explore the feasibility of concerted scientific and engineering
efforts in reducing the loss of life and property through programs
of public education and of effective early warning system. The
development of warning systems with adequate range of
monitoring instruments for the purpose of collecting necessary
data and information for disaster evaluation is necessary for
establishing relative potential risks.

32. • The development of warning systems with adequate range
of monitoring instruments for the purpose of collecting
necessary data and information for disaster evaluation is
necessary for establishing relative potential risks.
Communicate knowledge for people to be aware and get
prepared on these hazards. Through public education,
introduce precautionary measures to have public
awareness on preparedness against these natural hazards.
Disasters are inevitable, predictable, and expected; we
must be ready to face them. The time has come to fully
develop technology for convenient and immediate
dissemination of warning system to the public.

33. THE PHILIPPINE PUBLIC STORM
WARNING SIGNALS
• PSWS # 1
• METEOROLOGICAL CONDITIONS:
•  A tropical cyclone will affect the locality.
•  Winds of 30-60 kph may be expected in at
least 36 hours or
• intermittent rains may be expected within 36
hours. (When
• the tropical cyclone develops very close to the
locality a

34. • shorter lead time of the occurrence of the
winds will be
• specified in the warning bulletin.)

35. IMPACT OF THE WINDS
•  Twigs and branches of small trees may be
broken.
•  Some banana plants may be tilted or
downed.
•  Some houses of very light materials (nipa
and cogon) may
• be partially unroofed

36. • Unless this warning signal is upgraded during
the entire
• existence of the tropical cyclone, only very
light or no
• damage at all may be sustained by the
exposed
• communities.
•  Rice crop, however, may suffer significant
damage when it is
• in its flowering stage

37. PRECAUTIONARY MEASURES:
• When the tropical cyclone is strong or is
intensifying and is
• moving closer, this signal may be upgraded to
the next
• higher level.
•  The waves on coastal waters may gradually
develop and
• become bigger and higher.

38. • The people are advised to listen to the latest
severe weather
• bulletin issued by PAGASA every six hours. In
the meantime,
• business may be carried out as usual except
when flood
• occur.
•  Disaster preparedness is activated to alert
status.

39. PSWS # 2
• METEOROLOGICAL CONDITIONS
• A tropical cyclone will affect the the locality.
•  Winds of greater than 60 kph and up to 100
kph may be
• expected in at least 24 hours.

40. IMPACT OF THE WINDS:
• Some coconut trees may be tilted with few
others broken.
•  Few big trees may be uprooted.
•  Many banana plants may be downed.
•  Rice and corn may be adversely affected.
• Large number of nipa and cogon houses may
be partially or
• totally unroofed.

41. • Some old galvanized iron roofings may be
peeled off.
•  In general, the winds may bring light to
moderate damage to
• the exposed communities.

42. PRECAUTIONARY MEASURES
• The sea and coastal waters are dangerous to
small seacrafts
•  Special attention should be given to the
latest position, the
• direction and speed of movement and the
intensity of the
• storm as it may intensify and move towards
the locality.
•  The general public especially people
travelling by sea and air

43. • are cautioned to avoid unnecessary risks
• Outdoor activities of children should be
postponed.
•  Secure properties before the signal is
upgraded.
•  Disaster preparedness agencies /
organizations are in action
• to alert their communities.