Geography; Weather, Climate and Ocean relief

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  • Weather – Temperature, Pressure, Wind, Moisture, Cloudiness, Precipitation and Visibility at any given time.
  • Climate –
    • Average weather over a large area.
    •  Factors controlling weather and climatic conditions are:
      • Latitude.
      • Altitude.
      • Unequal distribution of land and water.
      • Ocean current.
      • Air pressure.
      • Wind.
      • Mountain barrier.
      • Nature of ground surface.
      • Atmospheric storms etc.
    • Different climate zones of the earth are:
      • Equatorial zone.
      • Hot zone.
      • Warm temperate zone.
      • Cool temperate zone.
      • Cold zone.
  • Composition of hydrosphere.
Storage componentTotal % of water
Oceans97.6
Saline lakes and inland seas0.008
Ice caps and glaciers1.9
Ground water0.5
Soil moisture0.01
Lakes0.009
Fresh water rivers0.0001
Atmosphere0.0009
  • Relief features of the oceans –
    • Continental shelf.
      • Shallow submerged extension of the continent.
      • Extends to a depth of 180 m.
      • Average width – 70 km.
      • Slope of – 10 / mile.
      • Covers 7.5% of the Oceans. (Atlantic Ocean – 13.3%, Pacific Ocean – 5.7%, Indian Ocean – 4.2% etc.)
      • 20% of petrol and gas is found here.
      • Provides the richest fishing grounds.
    • Continental slope.
      • Extends seawards from the continental shelf.
      • Max depth up to – 3660 m.
      • Average slope – 200 to 500.
      • Andesite line – Boundary between continental shelf and continental slope.
      • Covers 8.5% of the ocean area.
    • Continental rise.
      • At the foot of the continental slope, due to the accumulation of debris transported over the slope.
      • Average slope – 0.50 to 10.
      • Oil deposits occur here.
    • Deep sea planes. (Abyssal)
      • Most extensive part of the oceanic floor.
      • Average depth – 3000 m to 6000 m.
      •  Covers 75.9% oceanic area.
      • Occupied by raised ridges or submarine mountains and by very deep trenches or canyons.
    • Deeps. (Trenches)
      • Are narrow and steep side’s depressions.
      • Are formed when two plates moving together and one being pushed below the other.
      • Marina trench (Challenger deep) is the deepest trench at north-west Pacific Ocean near Philippines (approx 11 km deep).
    • Volcanic ridges.
      • Are of tectonic origin.
      • Formed by the volcanic activity along the spreading boundary of the plates.
      • These are thousands of km long and hundreds of km wide.
      • Their summits may rise as Islands. Example: Iceland, Azores Island etc.
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