HYDROMETEOROLOGICALHAZARD_(TYPHOON).pptx

Types of Hydrometeorological Hazards

1. HYDROMETEOROLOGICAL HAZARD

2. HYDROMETEOROLOGICAL HAZARDS are processes which involve the interaction of the atmosphere, bodies of water, and land and which pose threat to lives and human property. It is important to know how, when and where these hydrometeorological events operate because these occur more frequently and sometimes have even more far-reaching negative effects on the economy, the environment, and society as compared to any other type of natura disaster. This chapter explains the science behind the different hydrometeorological events so that citizens will be more aware of their nature and the dangers these present. While the government is actively working to make our islands better places to live in through research and development on such events and developing systems for early warnings and evacuation, individual awareness is still the most important preparation.

3. TYPHOONS PRESENTED BY: BLAIZE MARCY CAMACHO

4. A typhoon is a severe weather disturbance characterized by strong winds and heavy rains which revolve around a central low pressure area. Its the most powerful type of tropical cyclone that forms in this most western Pacific Ocean. The toad "yphoon" is most likely derived from the Chinese term "Tai Fung", which can be broken down into 4a; which means big and "fung", which means wind. It is lo ily known as bagyo, a term coined after Baguio City in Benguet Province where the wettest known tropical cyclone way back in 1911 hit and dropped approximately 2200 mm of rainfall for about three days. TYPHOONS: INTENSE TROPICAL CYCLONES

5. TROPICAL CYCLONES WIND SPEED Tropical depression up to 62 kph Troical storm ranging from 63-118 kph Typhoon greater than 118 kph Super typhoon exceeding 220 kph called "hurricane" in northeast Pacific and northern Atlantic regions) A typhoon is just one of three types of tropical cyclones. Tropical cyclones, which can be distinguished according to their maximum sustained-wind speed (over 10-minute periods),include the following major types:

6. The Philippines is the most frequently visited country by tropical cyclones —with a yearly average of 19 entering the Philippine Area of Responsibility (PAR) and 6 to 9 making landfall. The areas in the Philippines which are usually most affected by the action of tropical cyclones are: 1) northern and central Luzon and 2) the eastern Visayas islands.

7. The Philippines belongs to the northwest Pacific Ocean or basin, which is home to the most intense and most frequent occurrence of tropical cyclones. Here, tropical cyclones can actually form at any time. However, some seasonal variability of activity is usually has been observed through long years of observation. Tropical cyclone activity is usually lowest in May and increases from July until September, with the level of activity reaching its highest during August. Come November, the activity level eventually dies off. Notable, however, is that typhoon Haiyan (locally known as Yolanda), which is possibly the strongest typhoon in Philippine history, struck in November in2013. Death tolls allegedly reached more than 6000 according to the NDRRMC. SEASONAL VARIABILITY OF TROPICAL CYCLONE ACTIVITY

8. A tropical cyclone, on the average, has a total diameter of 550 km but can have a diameter more than 2000 km wide. Its basic structure is composed of an eye , an eye wall , and surrounding rain bands . TROPICAL CYCLONE STRUCTURE

9. The eye is the area of lowest atmospheric pressure in the structure of a tropical cyclone. Atmospheric pressure progressively decreases from the outermost portion toward the eye. In the eye, with diameter which may span 20-65 km wide, winds are weak, the temperature is warm, and the sky is clear- everything is calm and it is as if no weather disturbance is going on in the region over which the eye passes. EYE

10. The eye wall , the region immediately surrounding the tropical cyclone’s center and which can reach as high as 15km above mean sea level, brings the strongest winds, heavy rains, and turbulence shortly after the passage of the eye. EYE WALL

11. Rain bands are spiraling strips of clouds in the frines og tropical cyclones which are associated with rainfall. The winds of a tropical cyclone blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere due to the Coriolis effect. The Coriolis effect describes the deflection of an object's motion due to the earth's rotation about its axis. In the northern hemisphere, the air deflects to the right. In the southern hemisphere, the deflection is to the left. RAIN BANDS

12. Tropical cyclones form as a result of the atmosphere's natural tendency to maintain equilibrium by redistributing heat through wind from the equatorial regions to the polar regions. This mechanism prevents the tropical areas from getting excessively hot and the polar regions from becoming extremely cold. Why Do Tropical Cyclones Form?

13. If not for tropical cyclones, there would be severe environmental imbalances. Rainfall brought about by tropical cyclones replenishes ground water and surficial water. Flora and fauna in the Philippines are heavily reliant on tropical cyclones for source of water. In fact, almost 50% of the average annual rainfall in the country is derived from typhoon-related rainfall. On top of this, it would simply be too hot for life to thrive if not for the redistribution of heat which tropical cyclones facilitate. Importance of Tropical Cyclones

14. Tropical cyclones form both in the northern and southern hemisphere at latitudes 5- 30 degrees away from the equator(trade-wind belt) in parts of the ocean where water temperatures reach at least 26°C to depth of more than 60 meters. Toward the end of summer, when temperature difference between air at high altitude and the ocean surface is greatest, warm moist air forms the most. How Do Tropical Cyclones Form?

15. The air mass eventully increasingly heat up and rises, causing the atmospheric pressure and beneath to drop. Air masses from the surrounding higher pressure areas then tend to flow to this area of low pressure and also heat up and rise. However, mainly due to the Coriolis Effect, instead of traveling in a straight manner, wind swirls around the central low-pressure area. The rising humid air accumulates at cooler higher altitudes to form cumulonimbus clouds (dense, vertical, mushroom-shaped clouds associated with weather disturbances). But these also get dragged by the force of the incoming rotating air masses and form long swirling cloud bands. A point comes when the water vapor that form the clouds condense and cause heavy rainfalls.

16. At the same time, drier air from higher altitudes is sucked into the center of the tropical cyclone preventing the formation of clouds and, therefore, rainfall. This explains why the"eye" of the tropical cyclone is so calm. As long as there is warm air evaporating from the ocean, the tropical cyclone is practically like a machine operating on this supply of energy. The cyclone continuously grows in diameter, ranging from 150-500 kilometers, and height, ranging from 15-20 kilometers. But when the tropical cyclone reaches land, it is cut-off from its source of energy. Rainfall may continue, but the strong winds and turbulence wane.

17. Life span of typhoon A tropical cyclone typically has a life spant of nine days and can travel 10,000 kilometers. Tropical cyclones that form in the Pacific Ocean, usually tend to travel in a more west or west northwest direction, frequently affecting the Philippines. On the other hand, those that form in the South China Sea usually tend to travel in a more northward or northeast direction, still frequently affecting the Philippines.

18. Effects of Tropical Typhoons •Tropical cyclones are one of the most destructive natural phenomena worldwide. Countless casualties and indescribable damage to property in many countries are perennially brought forth by tropical cyclones. The effects of tropical cyclones are worst along coastal areas where they first make landfall. Tropical cyclones bring with them very strong winds, heavy rains, and can cause flooding and storm surges.

19. Strong winds, which cover a much larger area during tropical cyclones, cause the most obvious damage. Because the winds are strongest in the eyewall, meteorologists are on the watch for the locations where the eye (and consequently the eyewall) will make landfall. Wind usually slows down upon making landfall and reduces speed down to almost half its original speed 7 hours after crossing the coastline. This might not always be the case, as some do actually even pick up speed. STRONG WINDS

20. Storm surges, localized unusual increase of sea water level way above the predicted astronomical tide level, happens primarily due to intense winds and lowered atmospheric pressure that accompany intense tropical cyclones passing from the sea to the land. People living near the coast and rivers where water from the sea could potentially encroach are encouraged to flee inland as far and as high as possible, as early as the first warning of possible landfall. Storm surges resulting from more slow-moving and more intense tropical cyclones are expected to affect longer stretches of coastline. STORM SURGE

21. Heavy rains. Heavy rains, unlike strong winds and storm surges, actually occur in tropical cyclones of lower intensity. Flooding due to heavy rains is usually worse during tropical depressions and tropical storms. However, rainfall that accompanies tropical cyclones can also be beneficial. Rains brought about by tropical cyclones fulfill the water needs of some areas they cross. HEAVY RAINS

22. Determining areas prone to typhoon-related disasters. 2. Implementing legislation involving land use planning, zoning, and building. 3. Weather forecasting and monitoring MEASURES FOR MITIGATING THE DESTRUCTIVE EFFECTS OF TYPHOONS

23. •PSWS #1 - Tropical cyclone winds of 30 km/h to 60 km/h are expected within the next 36 hours. Its winds not expected to bring damage but may bring very light damage. 4. Effective public typhoon warning systems MEASURES FOR MITIGATING THE DESTRUCTIVE EFFECTS OF TYPHOONS

24. PSWS #2 - Tropical cyclone winds of 61 km/h to 120 km/h are expected within the next 24 hours. Light to moderate damage. MEASURES FOR MITIGATING THE DESTRUCTIVE EFFECTS OF TYPHOONS

25. •PSWS #3 - Tropical cyclone winds of 121 km/h to 170 km/h are expected within the next 18 hours. Moderate to heavy damage. MEASURES FOR MITIGATING THE DESTRUCTIVE EFFECTS OF TYPHOONS

26. •PSWS #4 - Tropical cyclone winds of 171 km/h to 220 km/h are expected within 12 hours. Heavy to very heavy damage. MEASURES FOR MITIGATING THE DESTRUCTIVE EFFECTS OF TYPHOONS

27. •PSWS #5 - Tropical cyclone winds of more than 220 km/h are expected within 12 hours.Very heavy to widespread damage. MEASURES FOR MITIGATING THE DESTRUCTIVE EFFECTS OF TYPHOONS