Transcript Lecture-14
Introduction • Relatively small, intensely developed low pressure cell that usually occurs over warm oceans. • Diameter-200-2000km • Characterized by a warm centre, very steep pressure gradients and strong cyclonic winds • Speed less than 60km/h-tropical depression • Speed ranges between 60 and 110km/h-tropical cyclones FORMATION • Developing tropical cyclone gather heat and energy through contact with warm ocean waters-5° and 20° North and South • Addition of moisture by evaporation of sea water from the sea surface powers them like giant heat engine • A wind pattern near the ocean surface that spirals air without inward Characteristics of tropical cyclone Structure of the storm centre • Centre or eye- calm, warm • Eye-extremely warm-as much as 10°C • Near sea surface air has same temp through out the storm • Wall of cloud(mainly cumulonimbus) rings the edge of the eye from sea level to heights of over 15km • Ring of the cloud-eye wall-most violent activity Eye of the tropical cyclone STRUCTURE OF TROPICAL CYCLONE Hurricane warning • Issued when a hurricane with sustained winds of 74mph or higher is expected in a specified coastal area in 24h or less • Maritime flags-two square red flags with a black square in the middle of each • Intensity or track of a forecast cyclone is uncertain-maritime flags-two square red flags with a black square in the middle of only one of them Effects of tropical cyclone • Destructive effects-heavy rain, strong wind, large storm surges, landfall and tornadoes • Remove forest canopy, change the landscape • Mudslides and landslides in mountainous areas • Plantations are leveled up, big trees are uprooted, settlements destroyedlose of life • Transportation and communication infrastructure • Standing water –spread of disease • Damage/destroy vehicles, buildings, bridges, overpasses and roads Effects of tropical cyclones World tropical cyclones • Northern hemisphere-August-October • South of the equator-February-March • Caribbean and South China sea-more affected • Indian Ocean-northeast monsoon • Bangladesh and eastern coast of India-Andra and Orissaheavy damage every year THANK YOU