typhoon classification

1. Formation of
Typhoons

2. Cyclones,Hurricanes,
Typhoons
Named according to region
a. Cyclones – formed over the
South Pacific Ocean and
Indian Ocean (moves
clockwise)
b. Hurricanes - formed over the
North Atlantic Ocean and
Northeast Pacific

3. Cyclones, Hurricanes, Typhoons
c. Typhoons (bagyo) – form over
the Northwest Pacific Ocean
 All produce similar effects
 In general, “typhoon”, “hurricane”
and “cyclone” are called tropical
cyclone

4. What is a tropical
cyclone?

5. typhoons are intense, rotating,
low-pressure storms
develop over warm, tropical
oceans
produce strong winds and heavy
rainfall
the appearance of the clouds in a
typhoon are in a spiral
arrangement; they are being
blown by winds in a counter-
clockwise direction

6. In our country:
 more typhoons pass by our
country from July through
October, although most of
the strongest typhoons
come on November

8. In our country:
 a tropical storm is divided into
five categories, namely
tropical depression, tropical
storm, severe tropical storm,
typhoon and supertyphoon

9. Category based on the
maximum wind speeds
Tropical Depression (TD) – 61 kph
Tropical Storm (TS) – 62 to 88 kph
 Severe Tropical Storm (STS) – 89
to 117 kph
Typhoon/Cyclone – 118 to 220 kph
Super Typhoon (STY) – above 220
kph

10. How is a typhoon
formed?

11. For a typhoon to form, the
following conditions must be met:
a. warm air
b. large body of water (ocean)
c. water surface temperature of
26.5˚C or greater
d. low air pressure

12. low-pressure area (LPA)
 a region where the air
pressure is lower than that
of the surrounding regions
and cause water from
the ocean to evaporate
more and faster

13. Movement & Speed Of Tropical Cyclones
Over the Philippine Sea,
Tropical Cyclones tend to
move on a general west-
northwest (WNW) direction
with an average speed of
19-20 km/hr.

15. The Eye, Eyewall, Rainbands
 The Eye - the clear, calm center of
storm, cool air descends into this
center (downdrafts)
 Eyewall – ring of thunderstorms
close to eye and where the strongest
winds are located
 Rainbands – curved groups of clouds
and thunderstorms, travel away from
eye in a spiral motion

16. Coriolis Effect
 force created by the Earth due to
its rotation causes rising currents
of air to spiral around the center
of the growing tropical cyclone
known to be the eye of the
typhoon

17. Coriolis Effect
 tropical cyclones in the northern
hemisphere rotate in a
counterclockwise direction while
tropical cyclones at the southern
hemisphere, rotate in a clockwise
direction

18. PAGASA gives the following
warnings and information when
there is a typhoon.
• Public Storm Warning Signals
(PSWS)
• gale warning
• amount of rainfall
• storm surge warning

19.  Gale warning is very important to
people who live near the sea.
Fishermen should always look at this
warning. If strong to gale force winds
are expected to affect a certain area,
fishing boats and other small sea craft
are advised not to venture out into the
sea because the gale may create big
waves which can easily destroy small
sea vessels.
a gale = a very strong wind

20. Storm Surges
 Occur when tropical cyclones reach land
 Storm surge – raised swell of water
- 60 to 80 km across
Around 2 to 5 meters higher than normal
tides
Created by heavy winds and cause flooding

21. Fujiwhara effect
sometimes referred to as Fujiwara
interaction or binary interaction, is
when two nearby cyclonic
vortices orbit
each other and close the
distance between the circulations
of their corresponding
low-pressure areas