Geography Component 1: HAZARDOUS EARTH

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  • Created by: Reemshah7
  • Created on: 15-11-17 22:23
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  • Geography Component 1: Global Geographical issues
    • Global Circulation
      • 1)warm air rises at the equator: low pressure 2)cool air falls: high pressure  3)as the air falls it warms again and flows back to complete a cycle
      • Ocean currents also transfer heat around the globe. Some ocean currents are powered by wind, resulting from the atmospheric circulation cells and others are powered by density differences due to differences in water temperature
      • In the Arctics, colder water is denser and therefore sinks, whereas warmer water  is at the surface
      • 1)Polar cell  2) Ferrel cell 3)Hadley cell 3)Hadley cell 2)Ferrel cell 1)Polar cell
        • Polar cell: high pressure  and the area is both cold and dry, so it can't hold much moisture
        • Ferrel cell: cool and wet climates
        • Hadley cell: low pressure, deserts and tropical rainforests are found here
        • This model is also referred to as the trial-cellular model of global atmospheric circulations
      • The wind regulates the earth and distributes heat energy
    • Natural climate change
      • An ice age, or glacial, is when the temperature is cooler for longer periods, so more of the earth is covered in ice.
        • The period today, is called the interglacial period, where it is much warmer.
      • Data and evidence for natural climate change, comes from ice cores, fossils, pollen and rock type.
        • Ice cores - these are cylinders of ice drilled from ice sheets and glaciers. The composition of the gases trapped inside the air bubbles are analysed by scientists. It tells them the levels of carbon dioxide and methane in the air at the time of the ice's formation
        • Rings inside trees - they tell us about about the temperatures in the past. Each layer varies in thickness. Cores are drawn, rather than chopping down trees
        • Plant pollen - pollen gets trapped and stuck in the mud. This enables scientists to work out past climates based upon the plants that grew in the past.
        • Rock types - if an area is covered in Till (a rock), it must have has ice on it in the past.
        • Fossils -  animals only live in particular climates
      • The change in the Earth's orbit every 100,000 years, are known as the Milankovitch Cycles.
      • Volcanic eruptions, pump ash dust into the atmosphere, causing a cooling effect.
    • Humans and Climate change
      • Human activities that can lead to global warming are industry, transport, energy production and farming
      • The enhanced green house effect is when greenhouse gases in the atmosphere trap some of the heat (necessary for life on earth), however, human activity increases green house gases in the atmosphere, leading to more warming.
      • possible consequences of global warming
        • biodiversity loss on land and in the oceans
        • more droughts lasting longer
        • coastal flooding, from sea-levels rises
        • spread of pests and diseases
        • more destruction, due to stronger hurricanes
        • loss of glaciers
    • Tropical Cyclones
      • tropical cyclones only form where seawater temperatures are above 26.5 degrees, in the tropics
        • Factors important in the formation of the tropical storm: high humidity, rapid cooling, low wind shear, Coriolis force and pre-existing low pressure
      • Key characteristics
        • Low pressure - very warm, moist air rises throughout the atmosphere
        • Rotation -the Coriolis force (spirals of wind) helps rise the air and drag strong winds
        • Structure - They form a cylinder of rising, spiralling air, surrounding an eye of descending, high-pressure air.
      • The Saffir-Simpson scale classifies tropical cyclones into five categories
      • Hazards and Impacts
        • Storm surges: as the tropical cyclone moves towards the coast, the sea get shallower. Water pushed up by the wind in front of the storm has nowhere to go but up and onto land.
        • Coastal flooding: storm surges can flood large areas of the coast if the land is low-lying.
        • Landslides: rainfall is heavy and intense during tropical cyclones, triggering landslides on slopes.
        • Hurricane Katrina caused 1836 fatalities, from a storm surge up to 8.5m high.
    • Tectonics
      • Layers of the Earth
        • Crust is solid and rigid - tectonic plates
          • Continental  crust - mainly granite, less dense than the oceanic plate.
          • Oceanic crust - mainly basalt and thinner than the continental plate
          • Both the continental and oceanic crust are less dense than the rocks of the asthenosphere
        • The  tectonic plates move to the top of the asthenosphere, under such high pressure that the rock flows
          • 1) the core heats the molten rock in the mantle to create a convection current
          • 2) heated rock from the mantle rises to the earths surface
          • 3) at the surface the convection current moves the tectonic plates in the crust
          • 4) molten rock cools and flows back to the core to be reheated
        • The lower layer of the mantle is liquid magma
        • The outer core is liquid iron and nickel
        • The inner core is iron. The pressure is so high that this is solid
      • Plate boundaries
        • Convergent plate boundary - two plates collide, one plate flows beneath another (subduction), causing earthquakes and volcanoes
        • Divergent plate boundary - rising convection currents pull crust apart forming volcanic ridge
        • Conservative plate boundaries - two plates sliding past each other at different speeds or directions, causing earthquakes
        • Collision plate boundaries - two continental plates collide and two plates buckle or are crumpled, causing earthquakes
        • Hotspots: points on the earth's crust with very high heat flow
      • Tectonic hazards
        • Earthquakes
          • Epicentre: the point on the surface directly above the focus
          • Focus: the central point where the earthquake begins
          • Earthquake magnitude: a measure of the size of the earthquake
          • Primary impacts: deaths and injuries, destruction of building and roads
          • Secondary impacts: landslides, spread of disease due to sanitation and tsunamis, when the earthquake occurs offshore
          • Seismic waves: the rings of vibrations that come from the focus. Measured by seismometers
        • Volcanoes
          • Shield - found on constructive plate boundaries or hotspots. Formed by eruptions of thin runny lava. Gently sloping sides with a wide base. Erupts frequently, but not violently
          • Composite  - found on destructive plate boundaries. Formed by eruptions of sticky lava and ash. Erupts infrequently but violently, including pyroclastic flow
            • Pyroclastic flow: mix of ash, gases and rock
          • Primary impacts: deaths and injuries, destruction of building and roads
          • Secondary impacts: atmospheric pollution caused by ash, mudflows, flooding if lava flows block rivers.
          • Preparing for eruptions - evacuating people and organising barriers to divert lava flows
          • Satellites are used to predict an eruption, by monitoring a change in heat activity
        • Managing Hazards
          • short-term relief - shelter and supplies
          • prediction
          • preparation - warning and evacuation, and building designs
          • long-term planning - training and funding emergency services

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