The document discusses tropical cyclones and their characteristics. It defines different categories of tropical cyclones based on wind speed and provides examples. Tropical cyclones form over warm ocean waters and typically move in a northwest direction. The Philippines is located in an area where tropical cyclones commonly form and the country's northern region is most affected.

1. the clouds are going around the center
of the typhoon in a spiral. The clouds are
being blown by strong winds.
Apart from rain clouds, typhoons
are characterized by winds that
go around a center.

4. If the wind speed is less, from 119
to 200 kph, then it is called a
typhoon. If the wind speed is
between 65 and 118 kph, it is called
a tropical storm. And when the wind
speed is between 35 to 64 kph, it is a
tropical depression.
categories of tropical cyclones
1. Tropical depression
2. tropical storm
3. typhoon,
4. supertyphoon

5. A tropical cyclone is a system of
thunderstorms that are moving around
a center. As the winds intensify or
weaken, the category is upgraded or
downgraded accordingly.
Table 1. Tropical Cyclone Categories
Category Maximum Wind Speed
kilometers per hour (kph)
Tropical Depression 64
Tropical Storm 118
Typhoon 200
Supertyphoon greater than 200

6. The term typhoon is used only in the
northwestern part of the Pacific Ocean. In
the northeastern part of the Pacific Ocean
and in the northern part of the Atlantic
Ocean, the equivalent term is hurricane. Thus,
a hurricane on one side of the Pacific Ocean will
be called a typhoon if it crosses into the other
side.
In the Philippines, we use the
same word for all categories of
tropical cyclones. We call it bagyo
whether it is a tropical depression,
a tropical storm or a typhoon.

7. Activity 1
Plotting the PAR
Objectives:
After performing this activity, you should be
able to:
1. read map,
2. given the latitude and longitude of
a tropical cyclone, tell if it has
entered the Philippine Area of Responsibility,
and
3. explain what is meant when a typhoon
has entered the Philippine Area
of Responsibility.

8. Materials Needed:
map of the Philippines and vicinity
pencil
Procedure:
1. Plot the following points on the map below
(Figure 2). Points Latitude, Longitude
a. 5°N, 115°E
b. 15°N, 115°E
c. 21°N, 120°E
d. 25°N, 120°E
e. 25°N, 135°E
f. 5°N, 135°E

9. 2. Connect the plotted points. The region
within is the Philippine Area of
Responsibility or PAR. It is the job of PAGASA to
monitor all tropical cyclones that enter this area.
Q1. If a typhoon is located at 15°N, 138°E,
is it within the PAR?
Q2. How about if the typhoon is at 19°N,
117°E, is it inside the PAR?
Answer: No, the typhoon is outside the
PAR.
Answer: No, the typhoon is outside the
PAR.

11. Under What Conditions do
Tropical Cyclones Form?

13. Where did the tropical cyclones
form? On land or in the ocean?
It is clear from the maps that all
four tropical cyclones started out in
the Pacific Ocean. Tropical cyclones
usually form where there is warm
water. The temperature should be 26.5°C
or more.
The warm ocean water heats up the air
above it. The warm air then rises. The
rising warm air results in a low-pressure
area. Air in the surroundings will then
move toward the area

14. Now, there is water vapor in the rising
warm air.The water vapor soon condenses
and heat is given off. The heat makes the
air rise even more,and air in the
surroundings will keep coming in. The
air starts to spin, and a tropical
cyclone is born.
What can you say about the
temperature of the bodies of water
in the vicinity of the Philippines? Is
the water warm or cold?

15. Our country is located near the equator.
Thus, it is warm in the vicinity of the
Philippines, both on land and in the
surrounding bodies of water. The warm
water supplies the water vapor that a tropical
cyclone needs to keep it going
In what direction did the
tropical cyclones move?
From the map, the students can see
that the tropical cyclones move in a
northwest direction. Not all tropical
cyclones move this way. But this is
the general rule for those that start

16. There are different reasons why this
happens. One, there could be a low-
pressure area in that region. So the
wind in the surroundings move toward
that region and the tropical cyclone is
carried along. Remember, winds blow
toward low- pressure areas.
Another reason is there could be a high
pressure area in the path of the tropical
cyclone. So the tropical cyclone cannot
proceed and is diverted along a different
way.

17. Which part of the Philippines was
hit by the four tropical cyclones?
All the four tropical cyclones hit northern
Philippines or the island of Luzon.Note
where the tropical cyclones start: at the
latitude of the Visayas and Mindanao.So
when a tropical cyclone moves to the
northwest, it ends up in Luzon.

18. This is the reason why Mindanao is
not commonly hit by tropical
cyclones. Unless the following happens: a)
the tropical cyclone starts at a latitude
closer to the equator, or b) the
tropical cyclone moves directly to
the west, instead of moving to the
northwest. This is what happened in
Mindanao in recent years.

19. In the case of Agaton, Yoyong, and
Huaning, where did they die out?
Near land or in the middle of the ocean?
Tropical cyclones weaken when they hit
land. They die out over land because they
need warm water to sustain them.
They need water vapor to keep them
going. Even when the tropical cyclone is
still in a body of water, it may weaken
and die out if the water is cold.