AICE marine science as level 2015-2016 Tropical Cyclones AICE marine science as level 2015-2016
Normal Wind Pattern
El Nino (southern oscillation) sequence of events occurring in southern Pacific Ocean Normal conditions cold nutrient-rich water flows North along west coast of S. America. Upwelling of nutrients due to winds from the South High productivity large numbers of: Anchovies Sardines Supports: substantial fisheries industry various sea bird species plankton-rich water (g) Discuss the causes and effects of El Nino event in the Pacific Ocean
Normal vs. El Nino
El Nino Conditions Every ~7-10 years Winds stop blowing from East or SE Warm equatorial water is blown by abnormal winds from the West. Pressure gradients in East and West Pacific are reversed Reverse in wind direction and equatorial currents Large area of warm water forms = cold-water species death Upwelling stops Nutrient supply to surface is reduced = lack of nutrients = primary production rapidly decreases Affects higher trophic levels Collapse of commercial fish stocks
El Nino Example Major event in 1982-83 Surface temps decreased by 5⁰C Heavy rain in normally dry eastern Pacific Cause not known: possibly global warming? http://player.discoveryeducation.com/index.cfm?guidAssetId=174A7F2E-4CF4-4704-AF3B-1566A0F0A744&blnFromSearch=1&productcode=US
Monsoons Asia = largest continent Climate swing: hot/wet to cold/dry Monsoon (rainy season) - seasonal shift in wind of the Indian Ocean Land absorbs heat faster than sea, so it heats up faster In winter, sea is warmed but not land Warm air over sea rises and is less dense Draws in cooler northeasterly air from land India: occurs during post-monsoon season: October - December (h) Explain the seasonal differences in temperature between the Asian continent and the Indian Ocean, and explain how these differences give rise to the patterns of monsoon winds.
Monsoon Summer (May-August) = land quickly heats and there is big temp. difference between Central Asia and Indian Ocean Land air warms, is less dense, rises Saturated air (water vapor) from southwest over Indian Ocean Thunderstorms Very heavy rain (80% of India’s annual) September, land mass cools, monsoon weakens & replaced with a dry, northeast post-monsoon
Tropical Cyclone Large mass of warm, humid, rotating air Thunderstorms, strong winds, & rain centered around a Low Pressure AKA: Tropical depressions, Tropical storms, Hurricanes, & Typhoons HOW TROPICAL CYCLONES FORM
Conditions Needed Warm water, @ least 26.5OC (79.7OF) Low Pressure Evaporationtropical air rises & expandscools until unable retain the moistureprecipitation When water vapor rises, it condenses & releases large amounts of heat energy, increasing evaporation & driving the development of the cyclone
Rotation & Movement Northern Hemisphere: Counterclockwise rotation Southern Hemisphere: Clockwise rotation Due to the Coriolis Effect & the way the winds are deflected as they approach the Low pressure Usually tropical cyclones develop near the equator & move westward & towards the poles (determined by prevailing winds)
Eye of Hurricane Wilma
What hemisphere?
Impact on Coastal Communities High wind Heavy rain Tornadoes Lightning Storm surge
Typhoon Sanba
Hurricane Sandy
Water spouts!
Hurricane Sandy
More from Sandy
Hurricane Irene Bahamas
Hurricane Ike, Galveston, TX
Hurricane Ike, Galveston TX
Hurricane Ike, Galveston TX