Lesson 1: About oceans

A thermocline is a distinct, thin layer in large bodies of water (oceans or lakes) where temperature drops rapidly with depth, separating warmer, well-mixed surface water from cold, dense deep water

Salinity

•Sea water is about a 3.49% salt solution, the rest is freshwater. 

•The more saline, the denser the seawater. 

•As the range of salt concentration in the ocean varies from about 3.2 to 3.8%, oceanographers refer to salt content as 'salinity', express salt concentration as parts per thousand; 34.9 ppt is the average salinity.

•As seawater evaporates the salt remains behind, only the freshwater is transferred from the ocean to the atmosphere.

•A region of excess evaporation, such as the subtropics tends to become salty, while the areas of excess rainfall become fresher. 

•Sea ice formation also removes freshwater from the ocean, leaving behind a more saline solution. 

•Along the shores of Antarctica this process produces dense water. 

•Salinity reflects the workings of the hydrological cycle: the movement of freshwater through the earth/ocean/atmosphere system.

The coriolis effect diverts any moving object (including water and air) to the right in the northern hemisphere and to the left in the southern Hemisphere.   

Knowing this, does the Coriolis force affect the direction of spiraling water in a toilet?

The Oceanic Conveyor Belt

A constantly moving system of deep-ocean circulation driven by a combination of thermohaline currents (thermo = temperature; haline = salinity) in the deep ocean and wind-driven currents on the surface.

Exercise

Write a a paragraph entitled the importance of the oceanic conveyor belt. Your paragraph must include a color, hand-drawn sketch map and as many of the following terms as possible:

• • Thermohaline circulation

  • Oceanic conveyor belts

  • Water density

  • Climate

  • North Atlantic Deep Water NADW

  • Antarctic bottom water AABW

  • Upwelling

  • Nutrients

  • Named oceans

  • Salinity

  • Atmospheric circulation

Post your paragraph and diagram here

The formation, distribution and physical impacts of hurricanes on coastal margins, including storm surges

Wait! According to this, shouldn’t Hurricanes spin clockwise in the Northern hemisphere and counter clockwise in the souther?

• When will a hurricane be classified as a disaster?

• Is there a correlation between storm strength and damage

• Can we predict hurricanes?

Impact Of Hazards

It is generally felt that that the less developed a country (LIC) is the more damage, both economically and in terms of loss of life the hazard causes.

1. Population: LICs have denser populations.

2. Finance: LICs do not have the financial clout to demand strict building legislation codes, unlike places such as USA.

3. Education: People in HICs such as Japan and the US are educated as to what to do in the event of a hazard, and where they can go, thus reducing the vulnerability of the population.

4. Insurance: Closely linked to finance. Homes in HICs can be insured against damage from hazards Offsetting the cost of rebuilding.

5. Economy: Many LICs are dependent on a cash crop economy. If a hazard wipes out their entire crop, then their whole economy will suffer.

6. Infra-structure: HICs are highly organised regards emergency services, and communications to ensure the population in need of help receives this as quickly as they possibly can reducing the spread of disease and death.

Of course, all of this is a broad generalization, and differences are much more subtle between regions:

• Some LICs have learned from past events and are now well adapted to cope with hurricanes

• Low income sections of HICs are highly vulnerable 

Case study of one hurricane and its impacts on coastal places and people

Typhoon Haiyan (N&C p. 61)

• Date: Nov 3 - 11 2013

• Category 5 on SS scale (Super Typhoon)

• Economic impact: US$ 4.5 billion 

• Fatalities 6400 +

• Location: Phillipines, Vietnam, HK, Taiwan, Guam, China, Palau, Micronesia

As you watch the video complete a 4P case study on the impacts on coastal places and people