Exam #3 Study Guide Lectures: 16-25Lecture 16 (October 29)What are oceanic gyres?Oceanic gyres are ocean currents from an anticyclonic circulation in each ocean and each hemi-sphere.Where are warm and cold currents?Warm currents are east of continents and cold currents are west of continents.What percent of heat occurs in oceans?In the Northern Hempisphere, 40% of heat transport occurs in oceans.Where is the warmest water found in oceans and why?The warmest water is typically found at the ocean surface because it absorbs solar radiation.What is thermocline?Thermocline is rapid temperature decrease with depth a few hundred meters below the surface.How close to freezing are deep ocean waters?Deep ocean waters are only a few de-grees above freezing even in the summer and near the equator.What is upwelling and what does it result in and where does is typically oc-cur?Upwelling is vertical transport of deep ocean waters upward which results in cooler surface wa-ter temperatures. Upwelling typically occurs along west coast of continents aka temperatures along west coast only reach upper 50’s - lower 60’s in the summer resulting in cooler summers along the west coast.What is El Nino?ATMS 100 1st EditionEl Nino is warmer than average water in the pacific ocean off of South America.What is La Nina?La Nina is cooler than average water in the Pacific ocean off of South AmericaWhat does ENSO stand for?Enso stands for el nino southern oscillation.What is southern oscillation?Southern oscillation is atmospheric oscillation over south pacific ocean. It encompasses both El Nino and La Nina.What are trade winds?Trade winds are easterly winds that blow along equator.What are normal conditions of ENSO’s?There is typically surface low pressure near Indonesia (resulting in clouds/rain) and high pres-sure near South America. This results in easterly winds across the Pacific aka Trade winds. Winds push the water from east to west and water is warmed by sunlight. Warm, moist air rises over western south pacific resulting in clouds/heavy precipitation. Air sinks near the wast coast of South America resulting in clear skies, little precipitation.What is the warm phase of ENSO?The Warm phase is El Nino. Here the pressure gradient weakens across equatorial Pacific. The reasons of this are unknown and easterly winds weaken. Warm water flows eastward across Pa-cific.Why is El Nino called El Nino?El Ninos typically reach their maximum around Christmas and El Nino means boy child refer-ring to Christ Child. Lasts for months, affects large areas, occurs every 2-7 years. What are effects of El Nino?Water temperatures may be 6 degrees celcius warmer than normal in Eastern Pacific. Warm wa-ter nutrient is poor because no upwelling resulting in dead fish and birds. Theres dry weather in the western pacific and wet weather in the eastern Pacific. Tropical cyclones increase in the east-ern/central pacific and decrease in western pacific and atlantic.What is the ENSO cool phase?The ENSO cool phase is La Nina. Hree the pressure gradient strengthens across equatorial Pa-cific. The reasons are unknown and easterly trade winds strengthen and cool water flows across the Pacific. Walker circulation strengthens resulting in more clouds/rain in the west and drier in teh east. Upwelling increases near South America.Lecture 17 (November 3)What is a tropical cyclone?A Tropical Cyclone is a low pressure system that develops over the tropical oceans of the world. They often move over into the middle latitudes or over land areas. They are the most destructive storms on the planet.Where do tropical cyclones form?Tropical cyclones form over most tropical oceans of the world but not right at the equator.Where do typhoons typically occur? Cylones? Hurricanes?Typhoons typically occur east of Asia. Cyclones occur Northwest/Northeast of Austrailia, east of Africa, and South of Europe. Hurricanes form east of North America and West of Mexico.How are hurricanes tracked?Hurricane tracks determined by large-scale mid/upper tropospheric flow pattern. The geostrophicwinds are at 200 mb.How are hurricanes named?Lists of hurricanes are used every six years alternating male and female names. There are seper-ate lists for each ocean basin. A storm is only named when it reaches tropical storm strength. If tropical cyclones causes a lot of damage or loss of life, its name is retired. For example, Andrew, Hugo, Ike, Ivan, Katrina, Rita, and Wilma.What are tropical disturbance/wave?Tropical distrubance or waves are clusters of showers and thunderstorms also known as African Easterly waves.What is tropical despression?Tropical depression is winds that are less than 39 mph or 34 knots.What is a hurricane?A hurricane is a strong tropical cyclone with winds greater than 74 mph and eyewall develop-ment.When are hurricanes most frequent?Hurricanes are most frequent between Augst and October.What are hurricane ‘ingredients’?Sea surface temperatures must be greater than 26.5 degrees. Deep later of warm water in upper ocean. Clusters of thunderstorms. Moist air in the mid-troposphere. Weak vertical wind shear. And latitude poleword of 5 degrees.Why are warm sea surface temperatures important for hurricanes?Warm water adds heat and moisture to the lower troposphere. The warm water must be deep be-cause hurricanes stir up to the ocean as they move across it. Large waves mix warm surface wa-ter with the cold deeper water.Why are thunderstorms important for hurricane development?They are important because they are cloud systems from which hurricanes are born. No thunder-storms means no threat of hurricanes. A hurricane can’t develop from clear skies. What are thunderstorms ITCZ?Belt of thunderstorms found near the equator. North east trade winds in the Northern Hemisphereconverge with SE tradewinds in the southern hemipshere.Why is moist air in the mid-troposphere important for hurricane develop-ment?The entrainment of dry air into circulation evaporates clouds and weakens the system.What is vertical wind shear and why is it important for hurricane develop-ment?Vertical wind shear is the change in the wind direction of wind speed with height. The stronger isit, the stronger the winds are aloft. This is bad for hurricanes because it rips them apart. They are more favorable for thunderstorms, tornadoes, and mid-latitude cyclones.What is the relationship between hurricanes and El Nino?Strong vertical wind shear over the Atlantic ocean during El Nino