Understanding Typhoons and Tropical Cyclones

Learning Goals

• Understand typhoon development and how landmasses and bodies of water affect them.

True or False

• Typhoons are larger than cyclones, which are larger than hurricanes. (False)
• Hurricanes are stronger than typhoons and cyclones. (False)
• Hurricanes, typhoons, and cyclones are the same but occur in different regions. (True)

Did You Know That...

• PAGASA (Philippines Atmospheric, Geophysical and Astronomical Services Administration) reports around 20 tropical cyclones entering the Philippine Area of Responsibility annually.

Typhoon Regions

• Hurricanes occur in the North Atlantic Ocean and Northeast Pacific.
• Typhoons occur in the Northwest Pacific Ocean, near the South China Sea.
• Cyclones occur in the South Pacific and Indian Ocean.

Tropical Cyclone

• Tropical cyclone is a general term for a rotating system of clouds and thunderstorms that originates over tropical or subtropical waters with a closed, low-level circulation.
• Tropical depressions are the weakest tropical cyclones.

Tropical Cyclone Occurrence

• Tropical cyclones occur annually during late summer in the Northern Hemisphere (July-September) and in the Southern Hemisphere (January-March).

Intertropical Convergence Zone (ITCZ)

• The ITCZ influences the location of typhoons.
• The ITCZ is observed at a maximum latitude of 20-25 degrees North in July and 20-25 degrees south in January.

Check Up

• How many typhoons enter the Philippines every year? (Around 20)
• What is PAGASA? (Philippines Atmospheric, Geophysical and Astronomical Services Administration)
• What is the difference between typhoons and hurricanes? (They are the same but occur in different geographic areas)
• Why are typhoons given a name? (The info is not included here)

Cyclogenesis (Typhoon Development)

• Cyclogenesis is the process of a cyclone's development and strengthening.
• Causes of tropical cyclones include pre-existing weather disturbances, warm tropical oceans, moisture, and relatively light winds.

Typhoon Formation Processes

• Evaporation of water on the ocean surface (26.5-27 degrees Celsius)
• Convergence of air masses with different characteristics
• High humidity
• Rising warm air cooling to form clouds
• Coriolis effect creating spin

Factors Weakening Typhoons

• Cold waters: reduce moisture, depriving the typhoon of fuel.
• Landfall: causes rapid cooling of the air, reducing intensity.
• Wind shear: differences in wind speed weaken the typhoon.

Typhoon Anatomy

• Eye: Central area of calm weather, clear skies, warm temperatures, and low atmospheric pressure.
• Eye Wall: Most dangerous part with strongest winds and heaviest rainfall.
• Rain Bands: Compact regions of vertical air movement surrounding the eye, forming clouds that spin.

Typhoon Effects

• Strong winds
• Tornadoes
• Rainfall and flooding
• Storm surge

Philippine Typhoon Proneness

• The Philippines lies on the western rim of the Pacific Ocean, north of the equator.
• It's surrounded by bodies of water (West Philippine Sea, Pacific Ocean, Bashi Channel, Sulu Sea, Celebes Sea) within the tropical zone.
• The tropical climate and monsoons (northeast from November to April and southwest from May to October) contribute to typhoon formation and frequency.