NAME OF THE TOPIC TROPICAL CYCLONE CLASSIFICATION OF TROPICAL CYCLONES Trop. cyclones are classified into 3 main groups,based on intensity: 1.Tropical depressions 2. tropical storms, 3. More intense storms, whose name depends on the region. For example, a tropical storm•In the N.W. Pacific referred to as a typhoon; •In the N.E.Pacific, or in the North Atlantic, it is called a hurricane. •In the S. Hemisphere or the Indian Ocean,It is called cyclones MEANING OF THE TERMS The word typhoon, which is used today in the Northwest Pacific, may be derived from Arabic ţūfān ( )طوفانwhich in turn originates from Greek Typhon (Τυφών), a monster from Greek mythology . The word hurricane, used in the North Atlantic and Northeast Pacific, is derived from huracán, the Spanish word for the Carib/Taino storm god, Juracán. The word cyclone means 'a turning wind with one eye' and comes from an old Greek story about a race of one-eyed giants called 'Cyclops'. TORNADO v/s Tornado has diameter on the scale of 100s of meters. It produced from a single convective storm (i.e. thunderstorm or cumulonimbus) It require substantial vertical shear of the horizontal winds to form and grow ( i.e. change of wind speed & direction with height) It is produced in regions of large temperature gradient. It is primarily an over-land phenomena tornadoes typically last on the scale of minutes TROPICAL CYCLONE Tropical cyclone has diameter on the scale of 100s of kilometers. It comprises of several convective storms. It require very low values (less than 10 m/s [ 23 mph]) of vertical shear to form and grow. It is generated in regions of near zero horizontal temperature gradient. It is purely an oceanic phenomena tropical cyclones have a lifetime that is measured in days CYCLONE V/S ANTICYCLONE TROPICAL CYCLONE A tropical cyclone is a storm system characterized by a low pressure center surrounded by a spiral arrangement of thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of watervapour containe d in the moist air. The term "tropical" refers both to the geographical origin of these systems, which usually form in tropical regions of the globe, and to their formation in maritime tropical air masses. The term "cyclone" refers to such storms' cyclonic nature, with counterclockwise wind flow in the Northern Hemisphere and clockwise wind flow in the Southern Hemisphere. The opposite direction of the wind flow is a result of the Coriolis force. All tropical cyclones are areas of low atmospheric pressure in the Earth's atmosphere. The pressures recorded at the centers of tropical cyclones are among the lowest that occur on Earth's surface at sea level. Tropical cyclones are characterized and driven by the release of large amounts of latent heat of condensation, which occurs when moist air is carried upwards and its water vapor condenses. This heat is distributed vertically around the center of the storm. Thus, at any given altitude (except close to the surface, where water temperature dictates air temperature) the environment inside the cyclone is warmer than its outer surroundings.© EYE AND CENTRE A strong tropical cyclone will harbor an area of sinking air at the center of circulation. If this area is strong enough, it can develop into a large "eye". Weather in the eye is normally calm and free of clouds, although the sea may be extremely violent. The eye is normally circular in shape, and is typically 30–65 km (19–40 miles) in diameter, though eyes as small as 3 kilometres (1.9 mi) and as large as 370 kilometres (230 mi) have been observed EYE WALL The eyewall is a circle of strong thunderstorms that surrounds the eye; here is where the greatest wind speeds are found, where clouds reach the highest, and precipitation is the heaviest. The heaviest wind damage occurs where a tropical cyclone's eyewall passes over land. Hurricane Isabel (2003) as seen from orbit during Expedition 7 of the International Space Station. The eye, eyewall and surrounding rainbands that are characteristics of tropical cyclones are clearly visible in this view from space. SIZE One measure of the size of a tropical cyclone is determined by measuring the distance from its center of circulation to its outermost closed isobar, also known as its ROCI. If the radius is less than two degrees of latitude or 222 kilometres (138 mi), then the cyclone is "very small" or a "midget“. Very large" tropical cyclones have a radius of greater than 8 degrees or 888 kilometres (552 mi). Size descriptions of tropical cyclones ROCI Type Less than 2 degrees latitude Very small/midget 2 to 3 degrees of latitude Small 3 to 6 degrees of latitude Medium/Average 6 to 8 degrees of latitude Large Over 8 degrees of latitude Very large MECHANICS A tropical cyclone's primary energy source is the release of the heat of condensation from water vapour condensing, with solar heating being the initial source for evaporation. Therefore, a tropical cyclone can be visualized as a giant vertical heat engine supported by mechanics driven by physical forces such as the rotation and gravity of the Earth What primarily distinguishes tropical cyclones from Extra tropical cyclones is deep convection as a driving force. Because convection is strongest in a tropical climate, it defines the initial domain of the tropical cyclone. By contrast, mid-latitude cyclones(Extra tropical cyclones) draw their energy mostly from pre-existing horizontal temperature gradients in the atmosphere. To continue to drive its heat engine, a tropical cyclone must remain over warm water, which provides the needed atmospheric moisture to keep the positive feedback loop running. When a tropical cyclone passes over land, it is cut off from its heat source and its strength diminishes rapidly. Scientists estimate that a tropical cyclone releases heat energy at the rate of 50 to 200 exajoules (1018 J) per day. This rate of energy release is equivalent to 70 times the world energy consumption of humans and 200 times the worldwide electrical generating capacity, or to exploding a 10-megaton nuclear bomb every 20 minutes.© Regional Specialized Meteorological Centers (RSMCs) There are six Regional Specialized Meteorological Centers (RSMCs) worldwide. These organizations are designated by the World Meteorological Organization and are responsible for tracking and issuing bulletins, warnings, and advisories about tropical cyclones in their designated areas of responsibility. In addition, there are six Tropical Cyclone Warning Centers (TCWCs) that provide information to smaller regions. Major basins and related warning centers Basin Responsible RSMCs and TCWCs North Atlantic National Hurricane Center (United States) North-East Pacific National Hurricane Center United States) North-Central Pacific Central Pacific Hurricane Center (United States) North-West Pacific Japan Meteorological Agency North Indian Ocean India Meteorological Department South-West Indian Ocean Météo-France Australian region Bureau of Meteorology (Australia) Indonesian Meteorological and Geophysical Agency Papua New Guinea National Weather Service† Southern Pacific Fiji Meteorological Service Meteorological Service of New Zealand FORMATION OF TROPICAL CYCLONES Map of the cumulative tracks of all tropical cyclones during the 1985–2005 time period. ThePacific Ocean west of the International Date Line sees more tropical cyclones than any other basin, while there is almost no activity in the Atlantic Ocean south of the Equator. MOVEMENT OF CYCLONES DUE TO WINDS RATHER THAN WAVES Although tropical cyclones are large systems generating enormous energy, their movements over the Earth's surface are controlled by large-scale winds— the streams in the Earth's atmosphere. In the Indian Ocean and Western Pacific (both north and south of the equator), tropical cyclogenesis is strongly influenced by the seasonal movement of the Intertropical Convergence Zoneand the monsoon trough, rather than by easterly waves. EFFECTS On land, strong winds can damage or destroy vehicles, buildings, bridges, and other outside objects, turning loose debris into deadly flying projectiles. The storm surge, or the increase in sea level due to the cyclone, is typically the worst effect from landfalling tropical cyclones, historically resulting in 90% of tropical cyclone deaths Over the past two centuries, tropical cyclones have been responsible for the deaths of about 1.9 million people worldwide. Large areas of standing water caused by flooding lead to infection, as well as contributing to mosquitoborne illnesses. © OBSERVATION In general, surface observations are available only if the storm is passing over an island or a coastal area, or if there is a nearby ship. Real-time measurements are usually taken in the periphery of the cyclone, where conditions are less catastrophic and its true strength cannot be evaluated. For this reason, there are teams of meteorologists that move into the path of tropical cyclones to help evaluate their strength at the point of landfall. Tropical cyclones far from land are tracked by 1.weather satellites capturing visible and infrared images from space, usually at half-hour to quarterhour intervals. (sample image on next slide) 2.Doppler radar- As a storm approaches land, it can be observed by land-based Doppler radar. 3. Hurricane hunters- Measurements in real-time, can be taken by sending specially equipped reconnaissance flights into the cyclone. In the Atlantic basin, these flights are regularly flown by United States government. These aircraft fly directly into the cyclone and take direct measurements of temperature, humidity & pressure inside the cyclone. infrared image of cyclone by satellite Infrared image of a powerful southern hemisphere cyclone, Monica, near peak intensity, showing clockwise rotation due to the Coriolis effect © FORCASTING The average wind through the depth of the troposphere, is considered the best tool in determining track direction and speed. If storms are significantly sheared, use of wind speed measurements at a lower altitude, such as at the 700 hPa pressure surface (3,000 metres above sea level) will produce better predictions. High-speed computers and sophisticated simulation software allow forecasters to produce computer models that predict tropical cyclone tracks based on the future position and strength of high- and low-pressure systems. However, scientists are not as skillful at predicting the intensity of tropical cyclones TIME Basin Season start Season end Northwest Pacific April January South Indian November April Northeast Pacific May November North Atlantic June November Australia Southwest Pacific November April North Indian April December CYCLONE SEASON IN INDIA The 2012–13 South-west Indian Ocean cyclone season is an ongoing event in the annual cycle of tropical cyclone formation. It began on November 1, 2012, and will end on April 30, 2013, with peaks in May and Nov. TROPICAL CYCLONE INTENSITY SCALE (NORTH INDIAN OCEAN) India Meteorological Department Tropical Cyclone Intensity Scale Category Sustained winds (3-min average) Super Cyclonic Storm >120 kt >222 km/h Very Severe Cyclonic Storm 64–119 kt 118–221 km/h Severe Cyclonic Storm 48–63 kt 88–117 km/h Cyclonic Storm 34–47 kt 62–87 km/h Deep Depression 28–33 kt 52–61 km/h Depression ≤27 kt ≤51 km/h RECENT MOST INTENSE CYCLONE IN NORTH INDIAN OCEAN Cyclonic Storm Nilam Formed Dissipated Highest winds October 28, 2012 November 1, 2012 3-minute sustained: 85 km/h (50 mph) 1-minute sustained: 100 km/h (65 mph) Lowest pressure Fatalities Damage Areas affected 990 mbar (hPa) 75 total At least $56.7 million (2012USD) Sri Lanka, South India Cyclonic Storm Nilam was worst tropical cyclone to directly affect south India since Cyclone Jal in 2010. NAMING MOST INTENSE CYCLONES Reading on Beaufort Scale 17 (for most intense cyclone) 10 min. sustained winds 136 knots(252 km/h) N E Pacific & N. Atlantic Category 5 hurricane N W Pacific Super Typhoon N. Indian Ocean Super Cyclonic Storm S W Indian Ocean Very intense Tropical Cyclone Australia & S Pacific Cat. 5 severe tropical cyclone MOST RECENT HURRICANE OF CATEGORY 5 Hurricane Sandy which hit the United States east coast in late October 2012, caused unprecedented damage, flooded subways, closed down all major airports, resulted in cancellation of over 15,000 flights, and claimed more than one-hundred lives. Ten states were declared disaster states. List of costliest Atlantic hurricanes 1 "Miami" 1926 $157 billion 2 "Galveston" 1900 $99.4 billion 3 Katrina 2005 $81.0 billion 4 "Galveston" 1915 $68.0 billion 5 Andrew 1992 $55.8 billion 6 "New England" 1938 $39.2 billion 7 "Cuba–Florida" 1944 $38.7 billion 8 "Okeechobee" 1928 $33.6 billion 9 Donna 1960 $26.8 billion 10 Camille 1969 $21.2 billion RECAPITULATION Q.1 From where the term “CYCLONE” came ? Q.2 which of the following is over-land phenomenon : 1) Tornado 2) Tro. Cyclone Q.3 which of the following is having low pressure at its centre1) Cyclone 2) Anti-cyclone Q. 4 Very large" tropical cyclones have a radius of greater than – 1) 2 degree 2) 8 degree 3) 18 degree Q. 5 what is the full form of ‘RSMC’ ? Q. 6 Name the recently occurred Hurricane which came in oct. 2012 ? THANK YOU PRESENTATION BY- I.D.SONI PGT-GEOGRAPHY K.V.TAGORE GARDEN,NEW DELHI