1. AICE marine science as level 2015-2016
Tropical Cyclones
AICE marine science as level

2. Normal Wind Pattern

3. 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

4. Normal vs. El Nino

5. 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

6. 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?

7. 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.

8. 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

9. 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

10. Conditions Needed Warm water, @ least 26.5OC (79.7OF) Low Pressure
Evaporationtropical air rises & expandscools until unable retain the moistureprecipitation
When water vapor rises, it condenses & releases large amounts of heat energy, increasing evaporation & driving the development of the cyclone

12. 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)

14. Eye of Hurricane Wilma

15. What hemisphere?

16. Impact on Coastal Communities
High wind
Heavy rain
Tornadoes
Lightning
Storm surge

17. Typhoon Sanba

18. Hurricane Sandy

19. Water spouts!

20. Hurricane Sandy

21. More from Sandy

22. Hurricane Irene Bahamas

23. Hurricane Ike, Galveston, TX

24. Hurricane Ike, Galveston TX

25. Hurricane Ike, Galveston TX