The document describes various weather instruments and their uses, including anemometers, barometers, hygrometers, radars, radiosondes, weather balloons, weather satellites, wind vanes, and thermometers. It also discusses different weather disturbances like drizzles, typhoons, tropical cyclones, and hurricanes. Monsoons, trade winds, and the intertropical convergence zone are explained. Public storm warning signals issued by PAGASA are outlined. Greenhouse gases, the greenhouse effect, and global warming are briefly covered.

2. Weather Instruments
INSTRUMENT DESCRIPTION
Anemometer Measures wind speed
Barometer Maeasures air pressure
Compass Used for navigation and for telling
directions
Hygrometer Measures humidity of the air

3. Radar Stands for Radio Detection and
Ranging; helps in locating storms,
telling their speeds, and determine
their extent
Radiosonde Measures the vertical profile of air
temperature,pressure and humidity in the
atmosphere up to an altitude of about
30km
Rain Gauge Measures the amount of rain that has
fallen over an area over a specific time
frame
Weather Map Shows the profile of the atmosphere
during a disturbance.

4. Thermometer Measures temperature; it can be made
with a liquid in a glass thermometer
Weather balloon Brings weather instruments such as
barometers and thermometers high up in
the atmosphere to describe their statets
Weather Satellite Surveys Earth and takes images of
Earth’s atmosphere as it moves around
Earth
Rain Gauge Measures the amount of rain that has
fallen over an area over a specific time
frame
Wind vane Tells wind direction

5. Weather Disturbances
• The Philippines has a unique set of weather
disturbances ranging from drizzles to thunderstorms
and typhoons.
• A drizzle is a light liquid precipitation whose droplets
are smaller than those of rain.
• A typhoon is a tropical cyclone that is formed
between 180˚ and 100˚E.
• The term “typhoon“ also refers to an extremely
powerful and destructive storm.

6. Weather Disturbances
• A cyclone is an area of closed, circular fluid
movement rotating in a counterclockwise direction
similar to Earth’s rotation.
• A tropical cyclone is a storm system that has low
pressure with many thunderstorms that may bring
about strong winds, floods, and storm surges.
• There are three general classifications of tropical
cyclones arranged in increasing intensity: tropical
depression, tropical storm, and typhoon.

7. Weather Disturbances
• The classification of the storms is based primarily
on wind speed.
• One basis for the classification is the Saffir-Simpson
hurricane scale.
• The hurricane is also a tropical cyclone that occurs
in the Western Atlantic.

8. Classification Wind Speed (kph)
Tropical depression Less than 63
Tropical storm 64 – 119
Hurricane/
Typhoon
1 119 – 153
2 154 – 177
3 178 – 208
4 209 – 251
5 Greater than 252

9. Weather Disturbances
• The Philippine Atmospheric Geophysical
Astronomical Services Administration
(PAGASA) is the country’s institution
responsible for tracking the sky.
• The Philippines started assigning Filipino
names in alphabetical order to storms in 1963.

10. Monsoons and ITCZ
Monsoons
are seasonal changes in atmospheric
circulation accompanied by corresponding
changes in precipitation.
These moving air masses, or wind, may be
hot or cold.

11. Two (2) Kinds of Monsoons
Northeast Monsoon (amihan)
experienced from November to April or May
characterized as a less srtong, northeast directed,
cool and dry breeze
formed as a result of air masses passing over the
cold areas of China, Siberia and Mongolia during
winter in the northern hemisphere.

12. Two (2) Kinds of Monsoons
Southwest Monsoon (habagat)
characterized as a strong, southwest-directed wind
that brings the Philippines significant rainfall
The warm air brought about by this monsoon is
associated with the breeze passing over large areas
of warm bodies of water during summer season
usually experienced from May to October

13. Trade Winds
are prevailing patterns of easterly surface winds
that occur in the lower portion of the atmosphere
these trade winds are eastern-directed in the
northern hemisphere and eastern-directed as well in
the southern hemisphere

14. Trade Winds
the northeast trade windcomes from the northern
hemisphere and blows toward the east
the southeast trade winds blows from the southern
hemisphere to the east as well
these two trade winds converge on an area over the
equator – this are of convergence is called the
intertropical convergence zone (ITCZ)
the ITCZ is a low-pressure area zone characterized by
showers and thunderstorms
areas affected by the ITCZ should expect rainfall and
thunderstorms

15. Public Storm Warning Signals
PAGASA provides a guide for storm warnings
in the form of public storm warning signals
(PSWS)
the warning signals describe the speed of the
storm and the lead time in an area

16. Public Storm Warning
Signal Number
Description Automatic Suspension
Guidelines
1 Wind speed of 60 kph
and expected within the
next 36 hours
No classes in
kindergarten
2 Wind speed of 60 kph to
100 kph and expected
within the next 24 hours
No classes in
kindergarten,
elementary, and high
school
3 Wind speed of 100 kph
to 185 kph and expected
within the next 18 hours
Noclasses in
kindergarten,
elementary, high school,
and college (including
graduate school)
4 Wind speed greater
than 185 kph and
expected within 12
hours

17. Greenhouse Effect and Global Warming
• Greenhouse gases are water vapor, carbon
dioxide, methane, nitrous oxide, ozone, and
CFC’s.
• These greenhouse gases contribute to the
measurable increase in Earth’s temperature- this
process is known as greenhouse effect.
• Global warming refers to the measurable increase
in Earth atmosphere, landmasses, and bodies of
water.