Brief Discussion of Previous Class (5:09 PM)

Siberian Type (5:15 PM)

• This is also called cool temperate continental
• 
• Summers are hotter, and winters are extremely cold and dry.
• This results in anti-cyclonic circulations.
• The rainfall is through the convection in summer, and through the snowfall in winter
• Vegetation is coniferous and is in the single largest stretch of vegetation on the earth.
• It is low in biodiversity but high in economic value.
• It is the only climate that is exclusively present in the northern hemisphere.
• Regions: Siberia, Russia, Poland, Scandinavia, Canada, Alaska

British Climate(5:30 PM)

• Cool Temperate Western Margin
• 
• They are under the influence of Offshore westerlies, throughout the year.
• This causes precipitation which is moderate throughout the year.
• They are under the influence of warm ocean currents, which keep their ports ice-free even during winter.
• It is known for its characteristic mild winter and cool summer.
• Vegetation is a mixed type, i.e. mixture of broad-leaf and coniferous.
• Regions: United Kingdom, Norway, the western coast of Western Europe, Western Canada, Southern Chile, New Zealand, and Tasmania.

Polar type of Climate (5:40 PM)

• It is also known as the Tundra type of Climate.
• It is covered with ice throughout the year.
• During summers when the snow melts, vegetation grows stunted, like mosses, sedges, and lichens.
• The rest of the region is covered with permafrost.
• Regions: Any region beyond the Arctic and Antarctic circles.

Koeppen Classification

Oceanography (6:03 PM)

• Ocean bottom Topography
• Ocean temperature
• Salinity
• Ocean Deposits
• Coral reefs
• Oceanic Currents and Circulations
• El Nino and related phenomena
• Tides

Ocean Bottom Topography (6:24 PM)

• 
• Continental shelf
• (a) These are submerged shallow portions of the continental crust with depths between 150-200 m
• (b) It is rich in sunlight, oxygen, and nutrients, which favours the growth of plankton.
• (c) The width of the continental shelf is dependent upon the slope of the adjacent land.
• (d) It is wider along the coastal plain, and narrow along the mountainous coast.
• (e) The continental shelf is rich in biodiversity and is known for its rich fishing grounds.
• Continental Slope
• (a) It is the boundary between continents and oceans, formed by the outer edge of the continents.
• (b) They are much steeper than the continental shelf
• Continental Rise
• (a) It is the base of the continental slope, with a lower slope.
• (b) It continues into abyssal plains.

Submarine Canyon (6:54 PM)

• These are the canyons, formed along the continental shelf and slope, because of the turbidity currents of the river, entering the ocean.
• Abyssal Plain
• They are also called Oceanic basins
• They are tectonically inactive oceanic floors, with relatively smooth surfaces.
• The average depth varies between 3000-6000m
• Seamounts
• These are isolated volcanic features and volcanic mountains formed due to volcanic activities, along hotspots and subduction zones.
• Volcanic Islands, Island Arc, Archipelago
• These are formed due to volcanic activities along the subduction zones and hotspots.
• (* Formation has been covered in Plate tectonics)
• Guyots
• While seamounts are sharply pointed, guyots are flat-topped hills, with summits below the water level.
• Mid-Oceanic Ridges
• They are formed along Ocean-Ocean divergent plate boundaries.
• Trenches
• They are formed along the Ocean-Ocean convergence and Ocean-continental convergence plate boundaries.

Temperature (7:17 PM)

• Differences concerning the Atmosphere
• (a) The water heats up slowly and cools down slowly.
• (b) The sunlight penetrates only upto 200m 
• (c) The albedo of the open ocean is low compared to land.
• (d) The temperature distribution through mixing is slower.
• Factors
• (a) Latitudes
• In Lower latitudes, higher insolation results in higher temperatures.
• Along, higher latitudes, lower insolation, and lower intensity cause lower temperatures.
• (b) Winds
• Winds help in the distribution of temperature across the globe.
• For Example, in the regions where westerlies are active, water temperature remains higher, than in the region of polar easterlies.
• (c) Ocean currents
• They help in heat balance, between the equatorial and polar regions.
• Warm ocean currents increase the temperature, and cold Ocean current decreases it.
• (d) Role of Landmass
• The seas which are surrounded will have higher water temperatures, than open ocean waters.
• Vertical distribution
• 
• The first layer is called Epilimnion (up to 200m)
• The second layer is called Thermocline (or Metalimnion) (200-1000m)
• The third layer is called Hypolimnion (beyond 1000m)
• Epilimnion:
• It extends up to 200m in depth.
• The average temperature is between 20-25 degrees celsius.
• It is a zone of constant sunlight and mixing due to winds.
• It is a zone of uniform temperature.
• It is the zone of Life
• Thermocline:
• It is the twilight zone, because of the very low amount of sunlight.
• The temperature decreases rapidly with depth.
• Hypolimnion:
• It is a zone of uniform and very cold temperatures.
• The average temperature is nearly 4 degrees Celsius
• It is because seawater attains maximum density at 4 degrees Celsius.
• It is also known as a dark zone.
• Horizontal Distribution
• The surface temperature lies between 20-25 degrees Celsius in tropical regions and decreases gradually towards the polar region.
• The three distinctive layers are visible along tropical regions.
• However, along polar regions, there will be a single uniform layer of cold temperature.

Salinity (7:50 PM)

• Salinity is the number of grams of dissolved salts in a thousand grams of seawater.
• It is measured as parts per thousand (ppt).
• The average salinity of Earth's ocean is 35 ppt.
• Sources of salinity
• Sources of addition
• (a) Sediments brought by rivers, which get dissolved over a long period of life.
• (b) Volcanic eruptions along the oceanic floor
• (c)  Evaporation in Ocean
• The salinity of oceans always remains constant.
• The factors increasing salinity are balanced by the factors decreasing salinity.
• Sources reducing salinity
• (a) Addition of river water
• (b) Rainfall
• (c) Ice melting
• (d) precipitation of salts along the oceanic floors.
• Dissolved salts in Sea Water (Decreasing Order): Chlorine, sodium, sulfate, magnesium, Calcium

The Topic for the Next class: Oceanography (continued)